Author: Okinoshima (US server)

The development of Britain’s cruiser tanks has always been a rocky, sometimes confusing series of missteps and red tape. An exemplary case of this was the long, and occasionally painful development of the A27M Cromwell cruiser tank, which took approximately two years to reach from its earliest order for an improved heavy cruiser tank by the British General Staff in 1940, to the production of the first A27M Cromwell prototype in January 1942. During this time though, many companies were involved attempting to get their designs through to production. Some, such as Vauxhall Motor’s A23, a shortened, lightened variant of Vauxhall’s infantry tank design, the A22 Churchill tank, were dropped early. While other designs such as Nuffield Mechanisation and Aeros A24 ‘Cavalier’, and the joint Leyland Motors and Rolls-Royce ‘Cromwell’ (that would eventually be taken over from as well by Birmingham Railway Carriage & Wagon Company), continued development. Even during these early stages, plans to improve on the ‘A27’ design were underway by its designers to adapt the A27 into other roles. One such plan was devised by Rolls-Royce to develop the existing A27 into an infantry tank but only use existing A27 plate armour. This new ‘infantry A27’ as it was called was given the General Staff number ‘A.28’. This was the first, of a long series of attempts to improve the basic Cromwell design that would continue well after the end of the war, culminating with the FV4101 Charioteer. This plan was likely conceived as an attempt to design a cheap, easier to produce infantry tank that would offer a commonality of parts to Britain’s cruiser tank force.

This is the only known drawing of the A28 “Infantry A27″

The design of the A28 was a simple evolution of the existing early Cromwell design, increasing the thickness of the the armour plate, but otherwise maintaining the same size, shape, angles, weight (somehow!?), gun and other components as the A27. In addition there was further consideration of increasing the A27’s armour even thicker beyond what was planned for the A28, described as “A27 armour increased to A22 (Churchill) thickness”. The changes are as follows with the A27 thickness first followed by the A28 and then the even thicker, A22 equivalent armour plans, in mm:

Front Plate: 57.15/76.2/76/2
Front Sloping Roof: 20/38.1/38.1
Front Sloping Floor: 25/38.1/38.1
Flat Floor Fighting Compartment: 14.27/14.27/19.05
Flat Floor Engine Compartment: 6.35/6.35/15.88
Front Vertical Plate (Driver’s Visor): 63.5/88.9/88.9
Fighting Compartment Roof: 17/17/19.05
Engine Compartment Roof: 14/14/19.05
Inner Side Plate: 14.27
Outer Side Plate Front: 31.75/26.97/26.97
Outer Side Plate Rear: 25/14.27/14.27
Skirt: 0/47.63/47.63
Hull Rear Plate: 38.1/50.8/50.8
Rear Sloping Floor: 20/25.4/25.4
Side Inlet Sloping Plate: 20/50/76.5
Air Outlet Sloping Plate: 31.75/40/25.4
Turret Front: 76.2/76.2/101.6
Turret Side: 63.5/63.5/88.9
Turret Rear: 57.15/63.5/88.9
Turret Top: 20/20/47.63

The project though was dropped in December 1941, not ever going further than the drawing phase of design, around the same time Rolls-Royce was finalising its design of the A29 Clan heavy cruiser tank. While the A28 was being filed away, this was hardly the last attempt to develop an infantry tank on the basis of the Cromwell hull, several other (mostly Rolls-Royce projects, notably the A31 and A32 and the previously mentioned A29 Clan) attempted to develop an infantry tank from a cruiser tank, the most famous being the joint Rolls-Royce and English Electric A33 ‘Excelsior’ which, unlike the A28, made it to the prototype stage with several being built with various experimental forms of suspension. The project would have eventually proved redundant regardless though, as throughout the production of the A27 Cromwell tank, new ways were developed to increase the protection and mobility of the original Cromwell design, notably the Cromwell VII and VIII, developments of the earlier Cromwell II which carried an additional 25-37mm of additional applique armour on the frontal hull and turret, providing an even greater level of protection than the A28 would have provided, other than the protection offered by the A28s armoured skirt.

Special thanks to famed, and incredibly nice tank historian, Pat Ware for additional help and expertise in the writing and direction of this article.

Citation:

British Tanks: The Second World War by Pat Ware
WO 291/1439 British tank data