WW2 British Armored Cars

Bison Mobile Pillbox

United Kingdom (1940)
Mobile Pillbox – ~200 Built

In the years since the Second World War, the Bison has been roundly mocked for being a terrible AFV and a bad idea. This is often held up as part of the ‘Declinist’ view of Britain’s war effort, an attempt to ridicule the entirety of the British armor design process or just as a meme on the internet. However, with an understanding of the context and the intended use of these vehicles, their merits and worth are apparent.

On the 18th of June 1940, Winston Churchill stood up in the House of Commons and gave the first of three speeches which would become some of his most famous works. One passage was:

‘Our Army and 120,000 French troops were indeed rescued by the British Navy from Dunkirk but only with the loss of their cannon, vehicles and modern equipment. This loss inevitably took some weeks to repair, and in the first two of those weeks, the battle in France has been lost.‘

He was, of course, talking about the evacuation from Dunkirk. The second sentence, where Churchill talks about the losses in equipment being made good, might seem quite peculiar, especially given the extent of the losses incurred in France. However, this was quite accurate, as the British war machine was rapidly churning out weapons to fill the ranks. However, the problem was the massive increase in the size of the armed forces. For example, the Home Guard was a quarter of a million men strong by the end of May. Three months later, it was a million men strong. Equally, the regular armed forces were undergoing massive expansion, and all of these new troops required weapons and equipment far in excess of what had been available even before the debacle in France.

On top of this situation, there was the threatened invasion by the Germans. While a daunting prospect for many in the English public and administration, the realistic chances of success of such an operation were non-existent at best. This was not common knowledge in the UK at the time, and the country lept to face the threat. This common drive was a useful tool for the British Government, as the emergency reinforced in people’s minds the need to come together, and that they were in a very real war. This enabled the complete conversion of the British economy to a wartime footing.

Mr J. G. Ambrose and Mr C. B. Mathews, founders of Concrete Ltd. Source:

Like most inhabitants of the UK, John Goldwell Ambrose and Charles Bernard Mathews turned their minds to the apparently impending German invasion after Dunkirk, and asked themselves: ‘what can we do?’ As they were the owners of Concrete Ltd, a company based at the Stourton Works near Leeds, they could do quite a bit more than most. Both Ambrose and Mathews were ex-Royal Engineers, and had served in the First World War. They had met each other when both began working on the problem of bunkers for the front lines and the time it took to erect them. Together, they had created pre-cast concrete bunkers which could be installed relatively quickly. After the First World War, they had formed Concrete Ltd, which specialized in the construction of precast structures. During the Invasion Scare, they hit upon the idea of using reinforced concrete pillboxes on the back of trucks. Mathews set the company to work and soon, a prototype was ready. This was demonstrated as a proof of concept vehicle to the military authorities, who gave some helpful criticism. The feedback was incorporated into the designs and production was begun. The vehicles were named after the logo of Concrete Ltd, a blue bison.

An unusual Bison. There are secondary sources stating there are more pictures to this sequence, and you can see it under construction. It is possible that this is the prototype Bison. Some modern historians suggest it is a third type of Bison, but it is the only time this style has been photographed, which raises questions about that suggestion.


No two Bison’s were alike, although they can be pigeonholed into two distinct types. It should be stressed that it appears the two types do not appear to be official designations, and are nomenclature added after the event by historians.

The first and more common design featured a separate octagonal bunker, which was elongated along its length, on the bed of a heavy truck, which could be either four- or six-wheeled. The driver’s cab and engine were protected by a thick square concrete body.

The partial reconstruction of a Bison. The bunker is original, however, the cab is made from fiberglass. The chassis also seems to be a bit too modern to have been used for a Bison, dating from just 1931. Source:

The other type of vehicle was a lengthened bunker that incorporated the flatbed and the cab into one structure, again on a heavy goods vehicle chassis. In both cases, the concrete was around six inches thick, which would have rendered the Bison immune to any contemporary infantry anti-tank or tank based gun the Germans had access to, apart from rare and extreme cases, like the 15 cm sIG 33 (Sf) auf Panzerkampfwagen I Ausf B, or other large caliber artillery pieces.

The second, rarer type of Bison, with the bunker assembled as a complete unit with the cab. Source:

These bunkers all had loopholes for armed men to fire from with their personal weapons, and had a coverage of 360 degrees, apart from the areas where the cab’s superstructure blocked them. Of course, the vision slits in the cab could cover this blind spot.

Total crew numbers, their dispositions during combat, and even what they were armed with was entirely down to the unit operating them, and what they saw as beneficial to their local conditions, although the weapons had to be of a personal nature, as the loopholes would not accept any mounted or crew-served weapons. The crew accessed the bunker through an opening cut in the base of the flatbed and reportedly climbed into the cab through the roof.

Due to the nature of the Bison, it could be adapted to any number of truck chassis, with a variety of engines, drive systems, and wheels. However, they all shared common features. They were of civilian stock, and all not useful to the current war effort. This would mean most of the trucks were of older designs, often dating back to the First World War, or earlier. There is even an example of a steam engine-powered truck being converted to a Bison, although, in this case, the steam engine and associated equipment were removed from the outset, and the chassis was designed to be a trailer.

It is unknown if the chassis were requisitioned, bought, or donated. While the Home Guard modified a great number of vehicles and operated even more, these were all arrangements between a local vehicle owner and the Home Guard unit in question. In the case of the Bison, it was an official program run by the government for use by the armed forces. This meant that a more permanent and official status would be required. Certainly, for the one vehicle for which there is something approaching a detailed history, the original owners never seem to have made any move to reclaim it, even when abandoned. This again suggests that ownership was obtained, and some form of reimbursement given by the Government by some means.


Although each Bison was a different shape, usually around the cab and bonnet, the means of construction were the same. When the donor vehicle arrived at the Concrete Ltd works, it was first stripped of all the bodywork and spare weight. Then, wooden shuttering was built up around the cab and bonnet. Into this, several layers of expanded metal were placed, then concrete poured in. On the flatbed of the truck, the precast bunker was installed. This was constructed in the same manner as the cab protection. Finally, a precast roof was attached.

The exact numbers of how many Bisons were produced are unknown. Several secondary sources suggest that the number was around 200 vehicles converted.

Bison Pillbox at Lincolnshire Aviation Heritage Centre. You can clearly see the expanded metal that was used to add strength to the preformed body. Source: Gary Binden, via Pillbox Study Group


The only hostile gunfire a Bison would ever encounter was in the imaginations of children playing over the discarded wreckage of Bisons. Even so, the Bison served an important role in both the RAF and the Army.

Army Service was very very limited. For example, there is one entry in the war diary of the 40th Royal Tank Regiment, where seven Bisons were collected from Leeds. This is dated to the 5th of October 1940. At the time, the 40th RTR only had two tanks on its strength, one light, and one cruiser. Thus, the Bisons seem to have been a useful addition, giving them some vehicles to train on, and the manpower of the regiment received a bit more muscle in case of an invasion. The Bisons are never mentioned again and it is likely they were discarded by the following year, when the regiment was shipped to North Africa. Except for this example, very little is known of their use by the British Army, which seems to have been meant as a jury-rigged expedient.

A veritable herd of Bison. These are all of the separated body versions, which was likely cheaper to make than the single unit type. Of note is the different arrangements of the bonnets, showing how each forward part of the donor chassis needed the concrete covering modified. Also, ‘Bison’ is written on the front of each vehicle. Source:

In regards to RAF service, even less is known, as just about the only sources we have are photographs of Bisons at assorted airfields. As with most ill-documented vehicles that served but never saw combat, it is quite difficult to give a clear idea of what they did. However, in the case of the Bison, there are reasonable details on one such vehicle, which will hopefully give an idea of their service and eventual fate.

This specific vehicle was based on a 1915 Leyland box van as a donor chassis, with solid rubber tires, and a chain drive. It was owned by a company called Cammocks, in Lincolnshire, and used as a removal van. In 1940, it was sent to be turned into a Bison. After being fitted with its concrete overcoat, it was sent to active duty at RAF Digby station, also in Lincolnshire. It remained at RAF Digby until the later part of 1944 when the station was downgraded to non-combat duties. At that point, the Army Transport Corps was tasked with its collection and removal to storage at Ferrybridge in Yorkshire. It is quite possible that a large number of Bisons ended up here.

As was the case with many Bisons, the weight of the modifications caused severe strain on the chassis. The Bison from RAF Digby was no exception, and the condition of the chassis was found to be extremely poor. Thus, the Bison was donated to the Home Guard, where it was moved about nine miles from RAF Digby to Quarrington near Sleaford. There, it was placed in a copse of trees and served as a bunker in support of a Home Guard checkpoint on the A15. On the 3rd of December 1944, the Home Guard was stood down, and the Bison was abandoned in the copse. At some point, a local farmer decided to salvage the chassis. The concrete parts were pulled off the chassis, with the bunker laying upside down on its roof. The chassis was converted to a farm trailer. The abandoned bunker in the copse of trees was well known locally and often played over by local children. In 1988, a local heritage society was tipped off about the strange bunker, and in 1991, the remains were recovered and placed on display at the Lincolnshire Aviation Heritage Centre.

Pictures taken of the Sleaford Bison just before recovery. There is an oddity in these remains, as the Bison at first glance seems to have two left panels for the cab. It is likely that one of the panels is actually from somewhere else on the cab, however, without a photograph of the original vehicle, it would be difficult to work out where. Source: Lincolnshire Aviation Heritage Centre (, colourized by Jaycee “Amazing Ace” Davis

Most other Bisons were likely scrapped or met similar fates. Today, only the remains in Lincolnshire and a half-authentic mock-up at Bovington Tank museum survive.

The Combat Role

The Bison should not be seen as a conventional AFV. The fact that some Bisons were reportedly constructed without a power plant, and even that the massive weight of the concrete modifications caused Bison engines to fail did not stop them from remaining in service. The Bison was a mobile pillbox.

Such a device was very practical for the defenders of the airfields where they were stationed. Any attack on the airfields would quickly run afoul of a Bison for several reasons. Firstly, the German Fallschirmjager would have an anti-tank rifle at their disposal at best, which would lack the ability to harm the bunkers, even assuming the Germans could get to their weapon containers. Secondly, the ability to move strongpoints about at random on the airfield grounds meant that planning any assault would be extremely difficult, as the attacker did not know in advance where the bunkers would be.

Other things could be done with a mobile pillbox. Flying from some airfields was a day time only event. Overnight, a Bison could be placed in the middle of the airfield, blocking the airstrip, and left there until flying needed to resume again. This could be done in order to prevent enemy airplanes from disembarking troops on the airfield in case of invasion.

A single unit Bison at RAF Speke, which is now John Lennon international airport in Liverpool. There may be another Bison on the far side of the De Havilland aircraft. It would be impossible to construct a permanent bunker in this location on the taxiway, but as the Bison can move, strongpoints could be placed covering the hangars. Source:


The Bison was not a typical AFV, but a mobile pillbox. In that role, Bisons provided a flexible defensive tool for the Local Defence teams of each airfield they were stationed at, and they provided it cheaply without drawing on any scarce resources, such as armor plate. They could also be used for training, when nothing better was available. Unfortunately, their use has been ill-documented and even the vehicles themselves have disappeared, with partial remains of just two vehicles surviving.

While the Bisons were a vehicle born out of a feeling of urgency and desperation, they made sense in the context in which they were built, and they provided supplemental defensive tools without drawing on important materials which were in high demand elsewhere.

Bison, Type 2. This type featured a separate fighting compartment.
Bison, Type 2. This type featured a separate fighting compartment.

Bison, Type 3, late model. As seen in a government photo from 1940/1.
Bison, Type 3, late model. As seen in a government photo from 1940/1.


Mace, Martin (July 2001). Vehicles of the Home Guard. Historic Military Press. ISBN 1-901313-08-5.
Wheels and tracks, Issue 41 (1992).
Lincolnshire Aviation Heritage Centre (

12 replies on “Bison Mobile Pillbox”

I had researched this for use in hypothetical Sea Lion scenarios for the game Panzer Leader, and am pleased to have reached most of the same conclusions. It appears that the RAF Regiment used Bisons in 1940 as one major element of airfield defense, the other being the Armadillo improvised armored truck, which was somewhat more mobile, if slow.

Minor, pedantic point: There was no RAF regiment in 1940. Each station had a Station Defence Officer, whom oversaw the local defence of the airfield.

I have researched the Bison Concrete vehicles for many years and was the finder of the Concrete pillbox now mounted on the truck at Bovington. I think others had seen it but I was the only one who fortunately knew what it was? There is also the remains of another broken pillbox located in the car park at Bovington as well, which also came from the same location in Yorkshire. My information is that the vehicles were used by the army in 1940/1, attached to RAF airfields who did Cadre courses on them. They were not used by the home guard! I am in the process of writing a book on the subject which I hope will be in print soon.

The ORB for RAF Martlesham Heath records a Bison arriving, details cab and separate rear construction! Was declared ” not much use” as any speed over 20mph caused tyres to blow! The rest section was dismounted and taken over by the padre as a chicken coop!! Cab and chassis removed by “Army”! Padre was upset when the rear section was “collected” to be reused! I am able to provide copies of these records of useful!!

AS luck would have it I picked up a document from Kew about Aerodrome defence only last weekend, which listed allocations of mobile machine gun posts. Yet to actually read it though.

Hi Ian, I would be very interested to obtain a copy, or read about this Bison. I have an extract from a book that tells of a Bison enroute to Martlesham Heath from Ipswich. Very Heath Robinson. I am in the (long term ?)process of writing the history of the Bison since finding the two Bison in Yorkshire many years ago. Also wrote and spoke to employees at Bison’s factory near Leeds who constructed these vehicles. New information is very rare so I would appreciate your help in any way possible

Any news on the Bison Pillbox vehicle? Does anyone know the Email or telephone Number of Ian Lisseman who wrote the short passage on the Bison at Martlesham Heath. I would be very interested to correspond with him about the Bison vehicle that was stationed there.

For your information:
I have been in contact with Ian Lisseman and he has updated me with the information that he had on the Bison that arrived at Martlesham Heath. His information is a continuation of the story of a Bison that puffed and wheezed into Ipswich and then shortly after left fo Martlesham Heath at 4mph! By his description I would say that the vehicle described is one of a number of Bison 1 (prototypes) There is another photograph of this type of vehicle which contains much barbed wire on the roof/top much like the description..

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