WW2 British Medium Tanks

Vickers Medium Mk.I & Mk.II

United Kingdom (1924)
Medium Tank – 286 Built

The early 1920’s were a difficult time for the British Royal Armoured Corps (RAC). Their First World War tanks were becoming worn down and obsolete. Equally, a series of projects designed in house, such as the Medium D, Medium C, and Light Infantry tank, had all failed. Other external designs such as the Vickers No.1 design had failed to be taken up.
This was a major issue to the RAC as the Treasury had provided a sum of GB£220,000 for the purchase of tanks to totally re-equip the RAC. If, however, a new tank could not be found then this money would be reclaimed by the Treasury, and any new purchase of equipment would be subject to new reviews. These would push the acquisition of new equipment back by years and leave the RAC with its First World War Mk.V Tank and Medium A Whippets well into the late 1920’s.
Then, in 1923, the army received two new tanks. Although unarmored, these tanks were the forerunners of a design that would see service all the way until at least 1941. These two tanks were the first of the Vickers Medium Mk.I, and almost no clue can be found to their origin. David Fletcher (Mechanised Force, p.8) suggests these tanks may have been created out of spare parts and designs lying around by Vickers in collusion with the War Office.
The only other clue might come from a copy of The Commercial Motor magazine of October 1933. In an article talking about a tractor, the designer of the tractor is introduced as Mr. C. S. Vincent-Smith, whom it is claimed designed tanks for the Army. This is the only tenuous link to the creation of the Mediums.

Medium Mark I Design

The first two tanks (one with the registration T15) were designated A.2E1, Tanks, Light, Mk.I. Later, as the design improved, the tanks were renamed to Tanks, Medium, Mk.I. Today, they are usually called the Vickers Medium Mk.I. A short time later, in 1923, a single A.2E2 arrived. This was named ‘David’ and had the registration T18. It was the only Close Support (CS) Mk.I variant ever built. Uniquely, it also mounted the sole 15-pounder tank mortar prototype.
The Close Support tanks were designed to fire smoke shells to cover the advance of friendly armor and protect them from enemy anti-tank guns. During this period, the weapon chosen was a 3.7” weapon that could only fire smoke. No other working round was produced. Although several other types of shell were designed, or designated, in effect the 15-pounder only ever had smoke shells.*
*For a complete story on the 15-pounder tank mortar, and its shell types see: Forgotten Tanks and Guns of the 1920’s, 1930’s and 1940s, ISBN 9781-5267-14534, By David Lister.

Mk.II* CS tank. Photo: SOURCE
On the gun tanks, the circular turret mounted a 3-pounder Mk.I, L32 gun, with a Hotchkiss machine-gun in a separate ball mount to the right of the turret. A visually distinctive feature of British armor of the time was the bevelling of the turret sides. The turret had three ball mounts for Hotchkiss machine-guns.
Two of these were placed about 180 degrees apart with the first one a few degrees to the right of the main gun. The third was placed on the aft right quarter of the turret. This meant that to bring a machine-gun to bare on a target to the front the 3-pounder had to be slewed off to one side. Two additional Vickers machine guns were mounted, one on either side, in the hull.
The V8 Armstrong Siddeley engine was mounted in a chamber separated from the rest of the fighting compartment on the left of the hull, with the driver sitting beside it. The driver’s head was in a cowl with a D shaped front plate that opened sideways. This plate hinged on the right side of the cowl, and mounted vision ports allowing the driver a view to the front, but was not intended as an entry or exit route. The rear plate of the hull mounted a large door on the right. This, along with two smaller hatches just in front of the Vickers guns, provided entry and egress to the crew.

Crew entering a Mk.IA*. Of note is the counter-weight on the back left of the turret, and the plated over opening of the third Hotchkiss machine gun location to the right of the counter-weight. Photo: SOURCE

Evolution of the Medium

The Medium went through several variants and two marks during its life. Often, these can seem confusing at a first glance. Identification is not made any easier by the fact that some components were retrofitted to earlier marks outside of the following official designations.

Author’s table

Identification Guide

As the Vickers Mediums are a complex subject with many submarks, this is a simple identification guide. First, it has to be determined if the vehicle is a Mk.I or a Mk.II. The three easiest ways of identifying this is to look at the tracks, front hull or main gun.


The clearest item is if the bogies are exposed or covered.

Front Hull:

Notice the shape and how the front hull looks bulkier and bigger on the Mk.II. Also, on the Mk.I, the roof of the driver’s hood is roughly in line with the roof of the rear part of the hull.

Main Gun:

The 3-pounder Mk.I has a shorter, stubier looking barrel. However, the easiest way of telling the two apart is the recoil recuperator (the tube under the gun barrel). On a 3-pounder Mk.I it sticks out much further, while on the 3-pounder Mk.II it is contained almost wholly within the turret.

Drivers Hatch:

The following image illustrates the differences between the driver’s hood for the Mk.I (left) and the Mk.IA and subsequent marks. On the Mk.I the entire hood is hinged upwards. On the later marks the hood is split into three parts, with the roof folding back and the sides folding outwards.

Commanders Position:

The ‘Bishops Mitre’ is the triangular shaped cupola that was added to the commander’s position. In the earlier tanks there was a simple two piece hatch. It was located further to the rear of the turret roof.

Turret Shape:

This image shows the bevel at the back of the turret that was introduced in the Vickers Mk.IA, and seen on the rest of the Mk.I series and the first Mk.II.

In the below image, one of the Hotchkiss machine-guns has been dismounted from the tank, while two more Hotchkiss machine guns remain in their ball mounts in the turret. These were added on the *(star) versions of both the Mark I and Mark II, replacing the turret Vickers machine-guns. A Vickers machine-gun can be seen in the hull of the tank. It is far bulkier than the Hotchkiss due to its water cooling jacket.

Photo: Getty

Medium Service

The Vickers Mediums equipped the RAC from about 1924 until the mid-1930s. At first, each of the four Battalions in the RAC were to have three CS tanks. However, for some unknown reason, these tanks were not produced. This led to the use of stand-in vehicles during exercises. To mark them as CS tanks, their gun was painted white and the letters ‘CS’ were painted on the turret.
During these exercises with the Experimental Mechanised Force, the Vickers Mediums were to have a profound effect, and seal the fate of the medium tank in the British Army. In 1927, they took part in an exercise against an infantry force. Both the commanding officers agreed that tanks needed speed and mobility as their priority, with firepower a close second. This would allow the tanks to overwhelm the infantry as they moved from a first tank proof location to another, or failing that allowed the tanks to relocate away from any enemy strong point where they had concentrated their anti-tank weapons, and attack where the line was weakest.
Medium tanks, moving at about 12-15mph (about the same speed as the later Churchill tank), were not seen as able to provide enough speed. It is from this exercise that the British thinking about tanks began to move towards the idea of the cruiser tank. In the early 1930s, some twelve tanks were converted to CS standards as the 15-pounder guns were manufactured.

Mk.I and Mk.IA* tanks masquerading as CS tanks during manoeuvres. Photo: Aviarmor
In 1933, a fifth battalion was created in Egypt, from personnel in two armored car companies. These were supplied with the ten Mk.IIA tanks, of which one was converted to CS. It appears two of these Mk.IIA* were still in service in 1940 when the Italians invaded Egypt. Both were reportedly used to help defend Mersa Matruh (not to be confused with the battle of the same name in 1942). From photographs, one appears to have been dug in as a turret bunker, the other appears to have been left exposed. However, there is no indication if this was because it was mobile or there was no time to dig it in.
In the UK, the remaining Vickers Mediums were mostly dragged out onto ranges and used as targets for anti-tank weapon testing. However, a few remained in service during the invasion scare period and were reactivated for use in defense of the UK.

Surviving Mk.II in the Tank Museum, Bovington. Photo: Mark Nash

Vickers in Foreign Service


Australia’s first tanks were a quartet of Medium Mk.II’s ordered in 1927, and arrived in 1929. These tanks were slightly modified as Australia did not use the Hotchkiss machine-gun. Therefore, the ball mounts that would normally be on the turret were replaced with Vickers guns in exactly the same locations. The AA machine gun and the bevel in the turret for this mount were removed. In addition, the Vickers guns had a much larger breech. In order to accommodate this, the bevels on the side of the turret were significantly reduced in size.
Between 1930-1937, these were the only tanks Australia had in the 1st Tank Section. They were used solely as training machines for the Australian Army to gain experience of operating tanks.
One such example exists in the Royal Australian Armoured Corps Tank Museum, Puckapunyal.

Two Australian Mk.II’s. Note the reduced bevel in the turret. Photo: AWM

A 1924 Medium Mk.I, equipped with radio and serving as a command tank during the 1927 manoeuvres at Salisbury plain.
Medium Mk.I with a thicker fake barrel to make it seem like a CS (Close Support) version. The CS tanks were usually tasked with creating smoke clouds to mask the tank and infantry advance from the enemy. This concept was still used during the North African campaign, nearly twenty years after.

Vickers Mk.II CS (Close Support), 1930.
Illustrations by Tank Encyclopedia’s own David Bocquelet

A Vickers Medium fitted with a radio set mounted in two boxes at the rear of the turret. Also note the aerial replacing the rear-top turret machine-gun mount.

Vickers Medium Mark IIA* fitted with asbestos plates on the outside to help with cooling in the scorching sun of the desert. These saw service in Egypt before WWII.
Illustrations by William ‘Rhictor’ Byrd, funded by Golum through our Patreon campaign


In the late 1930’s the British tank forces in Egypt were re-equipped with cruiser tanks. It is possible that some of the surviving Mk.IIA’s were handed over to the Egyptians so they could gain experience in operating tanks. The exact details of what happened in Egypt to the Vickers Mediums is currently unknown, however there were at least eighteen still operational in 1939, four in August 1940, and at least two were dug in at Mersa Matruh until early 1941.

South Africa

In August 1934, two Mk.I CS tanks were shipped to South Africa. One of these was ‘David’, the original CS tank. In the ten years after its delivery, it had been used for a variety of experiments including having its engine replaced with a new 120hp Armstrong Siddeley engine. This necessitated the rebuilding of its forward hull, and the first gear being disabled. After these trials were complete, the hull was once again returned to Mk.I standards and used as a training hull at Bovington, before being shipped to South Africa.
One tank survives at Bloemfontein barracks, but it is not known if it is ‘David’.

Soviet Union (USSR)

In 1931, the Soviet Union purchased fifteen Mk.II’s. These were called the ‘English Workman’ by the Soviets. Like the Australian versions, they replaced the Hotchkiss machine-guns with larger water cooled weapons, in this case Maxim guns. Thus the turret incorporated the same modifications to its shape. Only one was supplied fitted with a 3-pounder gun. As these were to see service, one presumes they would have been fitted with Soviet weapons. A number were sent to the Karelian Isthmus to be dug in as bunkers. About six of these were quickly overrun by the Finnish forces at the outbreak of the Continuation War, but were deemed useless and not recovered. Most likely because they were scrapped in place.

An ‘English Workman’, fitted with its Maxim guns. Photo: Aviarmor

Variants and Special Cases

Birch Gun

In the late 1920’s, several Vickers Medium Mk.II chassis were converted to self-propelled guns to take part in experiments into the future of armored warfare. These were fitted with an open fighting compartment onto which an 18-pounder field gun was fitted with a 360-degree traverse. There appears to have been at least three versions of the Birch Gun, the first with an exposed driver’s position and the second with a semi-enclosed driver’s position. The final version had a completely enclosed driver’s seat and a huge gun shield that almost fully enclosed the rest of the fighting compartment.
Some commentators state that the Birch Gun could double as an Anti-Aircraft gun, however, this is likely due to a misunderstanding. One of the batteries equipped with Birch Guns was given static AA guns to practice with before receiving its Birch Guns. This was likely as a Royal Artillery battery they needed some form of artillery to use for training and routine day to day tasks.

Final version of the Birch Gun. Photo: Public Domain

Mk.II Bridge Carrier

In 1926, there was an attempt to create a bridge carrier. A set of brackets was fitted to the outside of a Vickers Medium tank’s hull on both sides. These contained the components to create a short bridge. Upon arriving at an obstacle the crew would dismount and assemble the bridge before laying it over the obstacle.
Unsurprisingly, this was entirely useless as the crew would be exposed to enemy fire the entire time and so was never proceeded with.

The Mk.II Bridge Carrier. Photo: SOURCE

Tank, Medium, for Radio and Wireless

This conversion occurred in September 1926, and consisted of a large box body replacing the fighting compartment and turret. As the name suggests, it was used as a command tank to house several radios. It was named as ‘Boxcar’ officially, however, due to the dislike aimed at it within the ranks, it was nicknamed ‘Thunderbox’, a reference to an English slang term for a toilet.
Despite this dislike, in 1927 another four were ordered. However, the order was never completed.

The Communications variant of the Vickers Medium. Photo: SOURCE


This was an attempt to create a command tank as a cheaper alternative to Boxcar. Essentially, a Mk.II with a large box applied to the rear to house radios. While, at first glance, it appears to be similar to the Mk.II**, it lacked the other features of a Mk.II** such as the ‘Bishop’s Mitre’ cupola and the Vickers machine-gun. In the latter case, the Hotchkiss ball mount to the right of the main gun was retained.

Mk.I Wheel-Cum-Track

In 1926, T15, the first Mk.I delivered, was returned to Vickers. There, it was fitted with a set of subframes both front and rear. On these were a pair of wheels with solid rubber tyres. The idea was for the subframes to be lowered and a power take off engaged which would drive the rear set of wheels. Steering was done from a tiller bar inside the cabin.
As well as adding complexity to the design, the added mass would raise the tank’s total weight to over twelve tons. In addition, the wheels had to be placed inside the run of the tracks meaning the axle track was extremely narrow. This, along with the heavy weight, meant a high centre of gravity was balanced on a very narrow axle track. Unsurprisingly, this resulted in significant instability and the project was scrapped after a very short period.

Front view of the wheel-cum-track prototype. Photo: Public Domain.

Medium Artillery Tractor Mk.I and Mk.II

Know as ‘Dragons’, because of a play on words between the words ‘Drag’ and ‘Gun’. The exact date when the first of these was built is in contention. However, the Imperial War Museum’s website says 1922, which is before the Vickers Mediums were delivered. All sources agree that there is a link between the two, but which one came first is unknown and, considering the mystery of the Medium’s creation, it maybe that the Vickers Medium is based upon the Dragon.

Dragon Mk.I towing an artillery piece with full gun team. Photo: Overlord Blog

The Dragon Mk.II. Photo: IWM
Two of these were fitted with Rolls Royce armored car bodies and used in combat in 1941 to help defend RAF Habbaniya.

The two RAF Habbaniya Dragons, named Seal (Left) and Walrus (right). In this picture Seal has had her body changed from the original Rolls Royce armoured car style, and it is thought this is the configuration she saw combat in. Photo: Overlord Blog

This vehicle is HMAT Walrus, although she obviously bore another name at the time this picture was taken. HMAT stands for His Majesties Armoured Tank. At the time No1 RAF Armoured Car squadron used HMAC (His Majesties armoured Car) prefix for all their Rolls Royce armoured cars. Photo: Overlord Blog

Vickers Medium Mk.II specifications

Dimensions 5.33×2.78×2.82 m (17ft6 x9ft1 x 9ft3)
Total weight, battle ready 11.7 long tons
Crew 5
Propulsion Armstrong Siddeley V-8, [email protected] rpm
Speed 15 mph (24 km/h)
Range 120 mi (190 km)
Armament QF 3 pdr (47 mm/1.85 in)
2 x 0.303 Vickers machine guns (7.7 mm)
4 x 0.303 Hotchkiss model 1914 machine guns (7.7 mm)
Armor From 4 to 6.25 mm (0.16-0.25 in)
Total production 140 Mk.I & 167 Mk.II between 1924-1933

Links & Resources

Mechanised Force, David Fletcher ISBN 10: 0112904874 / ISBN 13: 9780112904878
Pen & Sword Publishing, Forgotten Tanks and Guns of the 1920s, 1930s, and 1940s, David Lister
Classic Military Vehicle Magazine #188

Forgotten Tanks and Guns of the 1920s, 1930s and 1940sForgotten Tanks and Guns of the 1920s, 1930s and 1940s

By David Lister

History forgets. Files are lost and mislaid. But this book seeks to shine a light, offering a collection of cutting edge pieces of historical research detailing some of the most fascinating arms and armament projects from the 1920s to the end of the 1940’s, nearly all of which had previously been lost to history.Included here are records from the UK’s MI10 (the forerunner of GCHQ) which tell the story of the mighty Japanese heavy tanks and their service during the Second World War.

Buy this book on Amazon!

WW2 British Medium Tanks WW2 Irish Armor

Vickers Medium Mk.D

United Kingdom/Irish Free State (1929)
Medium Tank – 1 Built

Ireland’s First Tank

The British company of Vickers was one of the biggest tank producers in the years leading up to the Second World War. In 1925, the company began production of their Medium Tank Mk.II and the Irish Free State (today the Republic of Ireland) were interested in purchasing a similar tank.
In 1929, Vickers built the Medium Mk.D, a derivative of the Mk.II built solely for the Irish Defence Force (IDF. Irish: Fórsaí Cosanta, officially: Óglaigh na hÉireann). Only one of these tanks was ever produced. It would be Ireland’s first tank and was adopted by the 2nd Cavalry Squadron of the Irish Cavalry Corps (Irish: An Cór Marcra).

A Cavalry Man sits atop the turret of the Mk.D. The Commander’s hatch is open behind him. Photo: Irish National Archives


The Mk.D was almost identical to the Mk.C which was sold to Imperial Japan in 1927. Any differences between the two models are not very well documented, but it seems the only major difference with the Mk.D was the addition of a cupola above the commander’s position in the turret.
What we do know is that the Mk.D was an upgrade of the standard Mk.II. It had a more conventional design, with the engine relocated to the back of the vehicle. The engine in this new compartment was more powerful than previous models. This engine was a water cooled, 6-cylinder Sunbeam Amazon petrol engine, rated at 170 bhp. This engine gave the tank a top speed of 20 mph (31 km/h).
The tank was of bolted construction, but the exact thickness of the armor is unknown. It would not be too far-fetched to assume it had similar armor properties to the Vickers Mk.II, which had armor of up to 8mm (0.31 in) thick. Other upgrades incorporated on the Mk.D and C for that matter included a slight elongation of the suspension and improved mud-chutes. The suspension consisted of 6 pairs of double-wheel bogies connected to coil springs. There was also a single track-tension idler wheel (jockey-wheel to Americans) on a single coil-spring in between the leading bogie and idler wheel at the front of the tank. There were 4 track return rollers and the drive wheel was at the rear.

Troops are instructed on the operation of the tank’s powerplant. The turret is traversed backward. Note the missing 6-Pounder gun which would otherwise be pointing over the engine deck. Photo: MMP
Armament was also different from previous models. The main armament consisted of a low-velocity 6-Pounder gun designed to fire High-Explosive shells in an infantry support role. This was in contrast to the higher velocity 3-Pounder guns being used on other British Vickers tanks. It was also armed with no-less than four Vickers water-cooled .303 machine guns. Two of these were located on the vehicle’s flanks. There was also one mounted in the turret bustle and another one on the left of the upper glacis.
The Mk.D had a crew of 5. This was composed of the Commander, Gunner, Loader, and Driver. The role of the fifth man is unknown, but he likely had the role of machine gunner. The driver’s position was rather exposed, as it was located behind a bulbous ‘nose’ at the front of the tank. The driver entered his positioned via a large door on the right of the ‘nose’. The rest of the crew entered via hatches on the flanks of the tank.


The Irish were relative latecomers to the idea of tank warfare. Prior to the 1930s, the only experience they had had with armored vehicles was with a few types of armored cars, which included the Rolls-Royce and Lancias.
The Mk.D was tested in the U.K. by Ireland’s foremost advocate of armored warfare, Lieutenant Sean Collins-Powell. The lieutenant was the nephew of the assassinated Irish revolutionary, Michael Collins. He was trained at Aberdeen Proving Grounds, Maryland, USA in tank usage and application. Collins-Powell took delivery of the tank, then accompanied it back to Ireland.

The Mk.D at the Curragh. The Commander’s cupola is clearly visible atop the turret. Photo: Aaron Smith

Vickers Medium Mark D
Rendition of the Vickers Medium Mk.D by Tank Encyclopedia’s own David Bocquelet


Unfortunately, not much is known about the Mk.D’s time in service with the Irish Army. We do know that it was assigned to the 2nd Cavalry Squadron of the Irish Cavalry Corps, based at the Cathal Brugha Barracks (Irish: Dún Chathail Bhrugha) in Rathmines, Dublin.

Irish troops surround the tank, listening to the instructor who stands at the driver’s position. The man is wearing the traditional ‘Glengarry’ hat of the Cavalry Corps. The turret is traversed all the way so what we can see here is its bustle and vacant Vickers MG position. Photo:
The tanks would have been used for gunnery and combined-arms training with infantry at the Glen of Imaal (Irish: Gleann Uí Mháil) in the Wicklow Mountains. 5,948 acres of the Glen had been used as an artillery and gunnery range since 1900.
In 1934-35, the Mk.D was joined in the 2nd Armored by two Swedish L-60 Light Tanks. The small and nimble light tank built by Landsverk surpassed the slow and cumbersome Vickers, which was now largely outdated in almost every way.

The Mk.D at the Curragh followed by one of the L-60. Photo: Aaron Smith


The tank was officially removed from active service in 1937. In 1940, the Mk.D was damaged beyond repair while attempting to cross obstacles constructed by the Engineering Corps in a training operation. There is evidence to suggest that the tank’s engine may have also caught fire.
Following this incident, the tank was scrapped. The 6-Pounder armed turret was kept, however, and placed as a static turret as part of defenses outside of Curragh Camp, Kildare, where the tank spent its final years. Only the gun still survives, it is currently on display at the Curragh Camp Museum.

The Mk.Ds gun, the only surviving piece of the tank. Photo: Tank Archives

An article by Mark Nash

Vickers Medium Mk.D

Dimensions 5.33 x 2.5 x 2.4 meters (17.5 x 8.3 x 8 feet)
Total weight, battle ready 14 US Tons
Crew 5
Propulsion Sunbeam Amazon 6-cyclinder gasoline engine, 170 hp
Speed 20 mph (32 km/h)
Armament Low-Velocity 6-Pdr (57mm) Gun.
4 x 0.303 Vickers machine guns (7.7 mm)
Armor Unknown
Total production 1

Links, Resources & Further Reading
Tiger Lily Publications, Irish Army Orders of Battle 1923-2004, Adrian J. English
Irish Army Vehicles: Transport and Armour since 1922 by Karl Martin
Mushroom Model Publications, AFVs in Irish Service Since 1922, Ralph A. Riccio

WW2 British Medium Tanks

Vickers Medium Mk.III

United Kingdom (1930)
Medium Tank (1927) – 3 Built

By the early 1920’s, the British Government’s enthusiasm for a state tank program had collapsed following the unsuccessful ‘Medium Mark D’. This project had eaten up the majority of the Government Tank Design Bureau’s budget and the widely overambitious model had been horribly unreliable. The exit of Winston Churchill from the Ministry of Munitions in 1921 was a key turning point in the downfall of publicly owned tank design in the United Kingdom. Military spending was falling as the troubled post First World War UK economy improved little in the 20’s and colonial duties bit away at what money there was, while the defense sector was slipping back into a conservative and skeptical stance. Within two years, the funding stopped coming and the nation that had invented the tank now left tank development to the private corporations.
Fortunately, the Vickers Company (that would become Vickers Armstrong in 1927) had begun competing with the Government over a contract for a replacement tank for the infantry in 1920. At the time the Mark D fell through in 1923, several prototypes of what would become the Mark I Medium had already been produced. The Mark I and Mark II vehicles produced throughout the 1920’s were indeed substantial improvements over the World War 1 era vehicles still in service. They replaced the last MK.V Heavies and Whippets as the 1920’s closed, being the only tanks mass produced in this period anywhere in the world, with a total run of just under 300 vehicles.

The previous Mk.II model on the left with the Mk.III on the right. Photo: Tank Archives Blogspot
These tanks incorporated a rotating turret and were more mobile that preceding tanks. While now it may seem trivial, this represented a leap in design with the three-man turret. This took the workload off the commander and main gunner (who in most vehicles of other tank building nations during the Interwar period were the same person) and would likely have had a serious positive influence in combat.
Despite these relative innovations, the vehicles had serious flaws. Some were quickly recognized others were not. Already in 1926, requests for an improved vehicle came from the War Office. The Mk.I’s and II’s had proved difficult to drive, and their top speed of only 15 mph (24kph), while meeting the requirement for a tank that was designed to primarily operate alongside infantry, still left something to be desired. While they were not mechanically as gremlin ridden as First World War vehicles, a number of improvements were suggested to make a more reliable vehicle. What may also have been more apparent to some military staff was that the mere 6mm of armor protecting these vehicles, which was less even than the Mk.I Heavies of 1916, would struggle to deflect even small arms fire at close range. More than twice this thickness was needed for a vehicle to reliably protect against even standard issue infantry weapons at close range. By September 1926, Vickers, requirements in hand, went to work.

Initial Design, the A.6

A weight limit of 15.5 tons was set for the new vehicles, so that they could be supported by the standard British Army pontoon bridge of the day. Easy rail transport, space for a wireless radio set, and (relatively) quiet running mostly for the benefit of crew wellbeing were also essentials. Later, easier steering ability and better protection were also requested. The initial design submitted by Vickers Armstrong was named the A.6, and based loosely on the A.1E1 Independent, which was still in testing at the time. One fad that this monstrosity briefly inspired was that of the multi-turreted tank. The A.6 design featured the same QF 3-pounder gun as the Mark I and II, but it was housed in a two-man turret, accompanied by three secondary machine-gun turrets. One was at the rear with an anti-aircraft machine gun mount and two at the front of the vehicle with two machine guns in each, although later this was reduced to one in each. The A.6 had 13mm of armor at the front and 7mm elsewhere. This kept the weight down to around 14 tons and it was estimated a 180hp Armstrong engine would propel the vehicle at 20 mph (32kph) on road.
In 1927, after the wooden mock-up was approved, the prototype was ordered, fitted with a new hydraulic ’Wilson Epicyclic’ steering gearbox. The three prototypes that were produced were fitted with the Armstrong V8 engines which exceeded expectations, and gave the vehicle a top speed of 26 mph, positively rapid for an interwar vehicle. Unsurprisingly, the machine gun arrangement was not well received on trials in 1928, and the vehicle was not judged to be far enough superior to the Mark II to warrant a serious production order.

The Revised Mark III

Determined to salvage the project, Vickers Armstrong ordered an improved vehicle in 1928, with two being built at the Woolwich Royal Ordnance Factory and another at Vickers. These featured slightly better armor, 14mm at the front and 9mm around, as well as a new turret capable of housing a radio set. The rear machine gun turret was abandoned, while the other two were shifted forwards to improve weight distribution. Better brakes were also fitted. From 1930 to 1933, further trials were far more positive. The vehicle was deemed more reliable, offered greater crew comfort and provided a more stable platform for the 3 pounder gun that the Mark I and II. Additionally, the top speed had further improved to a highly respectable 30 mph (48kph).
For all their work, the suspension proved somewhat overladen and the track components fast wearing out when used off-road. Finally, the 3 finished vehicles were purchased for use by the Royal Tank Corps and in 1933, entered service as HQ tanks. However, the high cost of the eight-year project more than outweighed its technical improvements, and no further orders were made. By the mid-30’s, British tank doctrine was moving on, and the Medium tank had no place in it. A Soviet purchasing commission came to look at British vehicles for export in 1930 and purchased a number of British tankettes and light tanks. At the same time, it appeared that, through the use of some skulduggery, they obtained fairly detailed information on the A.1E1 prototype and Vickers Mark III. After an investigation, a British Officer was court-martialed in 1933 for selling the plans on. It is sometimes claimed that the Mark III provided some design inspiration for the T-28 Medium Tank, of which more than 500 were produced and fought in the Winter War and opening stages of Barbarossa.

The Mk.III on the left with the similar A.1E1 Independent on the right. Note that they both share the void in the sides designed for the placement of a stretcher to evacuate wounded crew. Photo: IWM

Medium Mk.III
Illustration of the Vickers Medium Mk.III by Tank Enyclopedia’s own David Bocquelet

Brief Service

The last vehicle of the batch, ‘Medium III E3’, was used as a command vehicle for one of the largest combined arms training exercises of the era. On Salisbury Plain in 1934, this vehicle was used alongside other experimental armored and mechanized forces in the British Army, to test their potential and help find their role within the army in future conflicts.

A factory-fresh Mk.III. Photo: IWM
Ironically, the exercise this vehicle was used in would hurt British tank progress in the short term. The results were skewed by conservative officers who played down the role of the tanks in the exercise, an example of the disruption British tank design in the 1930’s faced. Some historians in the postwar era such as that of author and expert David Fletcher have gone so far as to suggest that these traditionalists, who were resistant to new practices in the army, used their positions to prevent the implementation of new tactics and equipment. They are accused of a ‘Great Tank Scandal’ which put Britain on the back foot of tank design as it entered World War Two.
The one silver lining for the participating Mark III, however, was that it was crewed by Brigadier General Percy Hobart, later ‘Sir’ Percy Hobart. He was an armor development expert who takes credit for designing some of the specialised tanks used for the D-Day landings that began the liberation of France in 1944. Perhaps some of his inspiration came from the ponderous tank he commanded around the training field on its only active duty in 1934. Shortly after the exercise, the participating vehicle was written off, another was destroyed in a fire, and the sole survivor remained in service around the training ground until 1938, and was likely scrapped some time within the next two years. Hence, sadly, none of the vehicles have survived to this day.

On the training ground towards the end of its service in 1938. Photo: Tank Archives Blogspot

An article by Will Hardwick


Dimensions 6.55 x 2.67 x 2.79 (21.4 x 8.75 x 9.15 ft)
Total weight, battle ready 16 long tons
Crew 6
Propulsion Armstrong Siddeley V8 180bhp
Speed 30mph (48 kph)
Range 120 Miles (190 Km)
Armament QF 3 pdr (47 mm/1.85 in)
3 x 0.303 Vickers machine guns (7.7 mm)
Armor 14 to 9 mm (0.55 to 0.35in)
Total production 3 (+6 A.6 Prototypes)
For information about abbreviations check the Lexical Index

Links, Resources & Further Reading

HMSO Publishing, The Great Tank Scandal: Part 1: British Armour in the Second World War, David Fletcher
Southwater Publishing, World War I and II Tanks, George Forty
Tank Archives Blogspot
The Imperial War Museum