It's telling the difference between the two that's the problem. Many military historians actually eschew too-close engagement with military technology, after one too many encounters with "rivet counters." I don't think that's a very helpful attitude, myself. If you're going to make an analytic point stand on the differing ways that the Germans and British used their heavy AA guns, then you need to know that the difference between the 3.7" (94mm) and 88mm AA guns. At the same time, when you read someone arguing that you need to understand a particular partial differential equation in order to "get" British tank transmissions in World War II, then you have an excuse. I can only think of one historian off the top of my head who has attempted to understand (a set of) PDEs in a historical way. It's a fascinating exercise, but it's far from clear who the audience for such an undertaking is supposed to be.
So when we talk about the history of the British tank, we're put in a schizophrenic place. How can you not talk about hardware? When the British official history tackled this problem, the editors made the very creditable decision to put the same medieval economic historian who wrote the history of British war production in charge of Design and Development of Weapons. Throw in two industrial historians (D. Hay and J. D. Scott), and you've got a team that can do justice to the questions that historians bring to the project as well as engineers.
One hopes. In reality, you've got bias built in. Just picking a medieval economic historian in 1950s Britain pretty much guaranteed that you'd get a quasi-Marxist ready and able to beat back the then-active school of technical journalists arguing that "British free enterprise won World War II, so what the heck's all this nationalisation about?") As for Hay and Scott, we've oh-so-cleverly picked the official historians of the Vickers group of companies. (IIRC, Google failing me right now). Again, there is wisdom to this, in that the Vickers group have designed and built a disproportionate number of British weapons over the years. The problem is that along the way, Vickers has fought off any number of outsiders intent on invading their turf.
I'm not going to argue against the company's expertise and insight into tank-building problems, Between 1927 and 36, between 22,500 and 93,750 pounds were spent annually on new tank development, and Vickers was the only firm involved. In the process, the government-funded research complex that we customarily denote as Woolwich Arsenal developed a process for welding hardened steel plate and a nickel-chromium-molybdenum steel suitable for welding. This was to armour Vickers tanks, to be sure, but the spin-off implications are not small, and the crumbs were well-positioned to fall Vickers' way. At the same time, while Dr. Merritt might be working on a tank transmission, he was not a Crown employee, but rather David Brown's top boffin. The article linked to above notwithstanding, I do not believe that we have a full understanding of what was going on here. As far as I can see, the Merritt-Brown transmission could not work without carbonitrided gears, and the potential of this technology ran far beyond tanks to everything from mine elevators to ship engines to the heavy-duty machine tools used for making armour. (I like these recursive formulations a lot, you can tell.)
So did Vickers get an inside look at these technologies and an opportunity to exploit them? I think so, although I've no intention of trying to prove it now. Then, in October 1936, the War Office published three specifications, for a light tank, cruiser, medium, and infantry tank, stipulating 14mm armour on light tanks, 30mm on cruisers and 60mm for infantry. The light tank was also required to have a gun and regenerative steering, and this put Vickers' existing 5.25t, 32mph Mk VI out of the running, even though, since the replacement was not needed urgently, due to a conceptual shift to a "scout car," it in practice became the last major British light tank of the war.
The Cruiser tank requirement came at the same time as the Wavell Mission to see the Red Army manoeuvres and was probably inspired by it. In spite of that, Vickers' A9 prototype satisfied the requirement. So, unbelievably, did its A10, supposedly an infantry tank, but ruled out for that role by the new armour requirements. In short, every tank that Vickers was then producing somehow met the army's needs. But what of the new tanks? Well, the Nuffield Motor Group was commissioned to build the new cruiser, in spite of having to buy existing outside engine and tank designs --both American in origin. The London Midland and Southern Railway shop got involved with a proposal for a tank with a British-designed diesel engine, later dropped in favour of a development of the flat Meadows engine that had gone into all the old Vickers tanks on the grounds that tanks should be low to the ground. Which was an official and well-found War Office position that you'd think would rule out orders for the American Liberty V-12 that went into the Nuffield tank!
Meanwhile Vickers designed the Matilda I as a fast entry into the infantry tank sweepstakes, of which crazy little design perhaps more anon. But the big contract went to a locomotive shop just outside Liverpool called the Vulcan Foundry, which ended up producing one of the real bruisers of 1940, Matilda II. In theory, though, there should have been one "tank circus" per corps in France in 1940, which would have amounted to more than 400 of these monsters. Instead, there were fewer than 30. So the question is, why?
Well, it's not much of a question, because Correlli Barnett already has an answer: British industry was in decline! Vulcan would be swept off into the ashcan of history in the later '50s, almost the last of the prime mover builders of the industrial North, thereby freeing up Liverpool lads to go into, I don't know, rock and roll or something. Computers? Computers would be good.
Only, I think that's the wrong answer. Next up: I interrupt this interminable lecture series with an even more boring film!