Experimental, United Kingdom, WWII

Cromwell II – The Lost Member of the Cromwell Family

Today we are taking a look at and clearing up the confusion around the Cromwell II, an odd vehicle that has become a convoluted mess of designations and theories, in part due to quite a confusing background. The vehicle’s correct details and information were found at the national archives, so we thought we should share this with our readers.

Its name implies that the Cromwell II was a replacement or upgrade of the Cromwell we all know, however this isn’t actually the case. Instead, it was created during the Cromwell’s development as an alternative design, one that would not actually end up being used.


Cromwell Origins

The origins of what would become the Cromwell begins back in 1940 when Britain looked to develop the replacement for the Crusader and Covenanter cruiser tanks. This idea led to a few designs: the A23 from Vauxhall, the A24 from Nuffield, and a third design submitted from the Birmingham Railway Carriage & Wagon works.

The A23 was essentially a lighter, more mobile version of the A22 Churchill, known as a Heavy Cruiser tank.

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The Nuffield’s A24 design was in many ways a beefed up Crusader, retaining the same engine, transmission and other parts which made retooling the lines a lot simpler. The Birmingham design was outwardly very similar but with different tracks, a longer suspension and updated shock absorbers.

Nuffield's A24 Cavalier.
Nuffield’s eventual A24 Cavalier.

These designs were submitted to the War Office and it was Nuffield’s cheaper A24 concept that won – whether this was due to merit or the misplaced favouritism running rampant at the time is open for debate. The first 6 tanks were ordered under the name Heavy Cruiser A24.

The Meteor Engine Arrives

However, in May 1941 Leyland had been working alongside the brilliant Rolls-Royce engineer William Robotham at the Clan foundry in Belper, attempting to convert damaged Merlin 3 V12 aircraft engines into tank engines, forming the Leyland Meteor. Leyland had been working on this engine for some time with the aim of fitting them into Crusaders, as it provided excellent, reliable power.

Robotham managed to fit two Crusaders with Meteor engines, with the Crusader maxing out at over 50 mph before shredding its tracks and hitting a tree. The point had been proven: the engine not only worked, it was far superior to the vintage Liberty and would be ideal for the new cruisers.

Meteor engine.
A Rolls-Royce Meteor Mark III. Image taken in The Tank Museum.

Shortly after Leyland suddenly got cold feet over the issue, saying that they had concerns over cooling issues which had so badly hindered the Crusader and Covenanter tanks. There is no evidence to suggest this was an issue with the Meteor, and it may have been backroom pressure from Nuffield who insisted on using the old Liberty engines.

Three Cromwells

Either way, these engine-related issues meant that three separate new cruiser tanks with varying powertrains were put into production, all with the name Cromwell. There was the A24 Cromwell I from Nuffield, the A27L Cromwell II from Leyland, and the A27M Cromwell III from Birmingham Railway Carriage & Wagon works.

The “L” in A27L stood for Liberty, its engine, while the “M” in A27M, as you’ve probably guessed, was for Meteor.

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Sometime during this fiasco somebody sensible at the Ministry of Supply noted that having three different tanks all called Cromwell was going to be a logistical nightmare, so new names were allocated: the A24 Cavalier, A27L Centaur and A27M Cromwell.

A27L Centaur cruiser tank.
Leyland’s A27L Cromwell II, later known as Centaur. This version was powered by the Liberty V12.

However, this is where Cromwell II, the focus of this article, causes some confusion. This is because Leyland’s A27L was also known as Cromwell II, but the two are actually separate designs. Our Cromwell II was built by Vauxhall, as a competing design with a different turret.

Much of the confusion arises because just going by its name, it seems that this vehicle was a later derivative in the A27M Cromwell family, such as with the Cromwell Mk1, Mk2, Mk3 and so on. It then all gets very complicated, as within these, you have subseries and different hull types A-F etc.

Cromwell II cruiser tank.
Vauxhall’s Cromwell II, which is often subject to confusion.

As you can see it was a bit of a mess. Once you add in the fact that those Centaurs we mentioned earlier were later given Meteor engines and renamed Cromwells, notably the Mk 3 and 4, you can see why it can trip people over.

So to make sure you don’t trip over: Leyland made the A27L Cromwell II, while Vauxhall made their own vehicle, also named the Cromwell II. Neither of them are later developments of other vehicles, but are of their own design.

Cromwell II

So, what was the Cromwell II?

While the whole Cromwell debacle was ongoing, a new turret was being designed by Vauxhall.

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This was due to the disappointing initial outing of the Churchill tank (also made by Vauxhall) and the original desire by some for them to drop the Churchill and join the Cromwell program.

Cromwell II cruiser front end.
As a Vauxhall creation, the Cromwell’s turret was similar in design to that used on the Churchill. They were not actually the same though.

Thus they began to design their own fittings and turrets for the Cromwell, but not the hulls. As they also designed Churchill turrets, their turret for the Cromwell would be quite similar, however they are not actually Churchill turrets as is sometimes quoted.

The new turrets – of which at least 2 were made – were of a composite type with a cast main body and a welded steel roof. The turret itself was not cast by Vauxhall at all, rather by two other firms.

The casted main body was made by the English Steel Corporation, who also made some of the early regular Cromwell turrets as well as the Tortoise casts later on. The plates at the top and bottom were made by the Whessoe foundry, who also welded the turret together. This piece was then mounted to a Vauxhall designed turret ring on a hull given to them, resulting in Cromwell II, made by 3 firms.

Cromwell II top.
The sides of the turret were cast, while the top was a rolled plate.

Apart from the new turret ring of which there is no real details, the only other obvious major difference is the Cromwell II had the distinct Vauxhall driver’s door, which was a single piece hatch designed to prevent snagging under the turret lip. The same hatch can also be found on the later regular Cromwell welded hull varieties.

Why Wasn’t it Used?

So what happened to this turret, and why did it not enter service? Well that’s down to a few reasons.

The first was while Vauxhall was planning to switch to Cromwell from Churchill, the Churchill proved to more or less be adequate after some pretty extensive overhauls.

Add in the fact with delays around the Meteor, with it entering service 2 years later than it should have, then one can argue that Vauxhall simply had better stuff to do.

Cromwell II rear.
Delays with the Cromwell project meant Vauxhall put resources elsewhere.

Also important were the results from the firing trails.

The first of these took place with turret 001 – this was mounted on the Cromwell mockup hull without running gear or guns fitted on the 9th of September 1943.

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The vehicle was struck with a mixture of rounds, from small arms to 25-pounder high explosive – overall the turret performed well. A notable issue was found on the pistol port, which allowed splash from small arms fire to enter and was marked up for needing improvement.

Cromwell II right side.
The Cromwell II’s cast turret armor provided good protection, but some areas, such as the bulge at the bottom, were noted for improvements.

The bigger issue was the lower bulge around the turret which deflected rounds down into the upper deck if struck roughly 1 inch above it. This aside, they felt that the welding held up well, and the armor itself was sound.


The original prototype next appears at Shoeburyness on the 8th of September 1944, where it underwent firing trials to test various fittings for in-service Cromwells. They record the vehicle as number 2638, so we can confirm its the same vehicle, but it was no longer in running condition. The vehicle was fitted with a turret ring traverse gearbox bolted to the inner turret wall, and tests were carried out to see how it reacted to being stuck by 25-pounder HE rounds.

The final pictures of the tank are seen in July 1945 at the same range, where the vehicle is once again used as a test vehicle, this time to record the damage done to tillers and drivers apparatus inside the lower nose from shot and mine attacks. At this point the vehicle is in a sorry state and it appears the turret has been dislodged at some point and the track guards are missing.

Cromwell II number 2638.
Cromwell II number 2638 in a sad state after firing trials.

The name the “Jinx” has been added to the turret, possibly as it brought bad luck? Either way the hull was subjected to several shots, and measurements were taken before they detonated mines under the forward left side.

After this the vehicle disappears from history and today no trace is left of either of the Cromwell II turrets, save a few photos and this information tracked down in the archives.

Remaining Mysteries

There is still one oddity which has yet to be explained, and that is the upside down and incorrect casting number on one of the Cromwell II turrets. This is seen on turret 2, which was fitted to the display model.

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This turret is rather odd in that not only does it share the same C70000 serial number on one side as turret number 1, but that on the other side of turret 2 is a different cast number. All other turrets have this the right way round and matching numbers on either side – a casting mistake at the factory perhaps?