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I have some notes I made on British interwar tank development: kind of a general summary.
Medium Tanks
During the 1920s Britain remained at the forefront of tank design, with the Vickers Mk I and II medium tank. This was comparatively fast (24 kph) and well armed with a 47mm gun in a rotating turret along with multiple machine-guns. Its main disadvantage was the thin armour, at just 6.5mm only capable of resisting rifle-calibre bullets. It weighed 11.7 tons. 168 were produced in total, making this by far the most common medium tank in service anywhere in the world in the 1920s.
Vickers Mk I tank, entered service in 1923
At the end of the 1920s Vickers also produced a smaller and cheaper medium tank, officially called the Vickers Medium E but more generally known as the "6-Ton Tank". This was designed for export, and many were sold abroad although the British Army did not acquire any itself. It came in two versions, one with a 47mm gun and coaxial machine gun, the other with two turrets side-by-side, each mounting a single machine gun. Vickers themselves produced 153 Medium E Tanks - but the Soviet Union copied the design, renamed it the T-26, and produced no less than 12,000 of them in the years 1931-41. The Polish 7TP tank was also a copy of the Medium E, but unlike the Soviets, the Poles did pay royalties to Vickers for using the design!
Vickers Medium E, the "6-Ton Tank"; twin-turret version
Soviet T-26, copied from the Medium E
Tankettes
Another development of the 1920s was the tankette, produced on a private basis by the Carden-Loyd Tractor company and then by Vickers. Very small (less than 2 tons) with a 2-man crew, fast at 40 kph but armed with only a single forward-firing machine gun, they were designed for reconnaissance and infantry support. The British Army acquired about 300 of them in the late 1920s, but then decided their combat performance was inadequate; and the design was abandoned in British service. Many other countries, however, saw the Carden-Loyd tankette as a cheap and cheerful way to acquire an armoured force without going to the expense of building 'proper' tanks, and Vickers exported large numbers of these vehicles - to Poland, Czechoslovakia, the Soviet Union, France, Italy, Netherlands, Belgium, Finland, Portugal, Greece, Bolivia, Chile, Japan, China and Siam.
A two-man Carden-Loyd Tankette Mark VI
New Doctrines
In the early 1930s Britain developed its tank doctrine further, and decided that three main types of tank were necessary. Note that it is clear they were still thinking in terms of WW1, and assuming battles would consist of assaults against heavily-defended enemy trench lines, followed by a breakthrough phase into open countryside.
Infantry tank - designed to accompany foot soldiers across No-Man's Land and break through the enemy trenches. Speed and range were irrelevant since an infantry tank would only have to move at human walking pace; but it would need to have exceptionally heavy armour since it would be the focus of every enemy gun in range. Its weapons were primarily intended for use against enemy infantry and bunkers.
Cruiser tank - designed for the exploitation role once enemy resistance had been broken by the main assault. Speed and reliability were vital; armour was less important since these tanks would be expected to bypass dug-in enemy positions, not attack them head-on. Weapons were designed for use against enemy tanks as well as soft targets.
Light tank - small, cheap and fast. Designed for use in the scouting and reconnaissance role, and not intended to stand and fight against an organised enemy.
(Note: Guderian's initial plans for the Wehrmacht's tank force were remarkably similar. He was forced to simplify his scheme because Nazi Germany lacked the capacity to produce so many different models of tank, and so instead focussed on multi-purpose designs. Ironically, this proved to be a better choice in practice.)
At first, the Vickers company produced tanks in all three categories. However, from 1937 the British government decided on a deliberate policy of expanding the country's tank production capability instead of relying on a single supplier. Contracts were placed with many other manufacturers, in order to give them experience in tank production that could then be scaled up in the event war came.
Unfortunately this policy - while well-intentioned and seeming like a good idea on paper - was a failure. The quantities of tanks the other companies were asked to supply - 40 here, 50 there - were too small to make it cost-effective for them to set up a dedicated production line. Instead, they temporarily switched over their existing manufacturing plant to make the tanks - which was slow and inefficient compared to what a purpose-made factory could have achieved. The result was that when WW2 did break out, British tank production was split between multiple small-scale and inefficient manufacturers with little specialist expertise. The comparatively dire state of British tank design during the war years can be blamed in large part to this policy decision. (By 1945 Britain was finally able to produce tanks like the Comet and Centurion which were a match for anything other countries had in their armouries - but that was too late to have much effect on the outcome of the war.)
When the Second World War broke out, Britain's tank force was divided between the following models:
Infantry Tanks
Infantry Tank Mk I A11 (Matilda I) - 10 tons, 13 kph, front armour 60 mm, 1 MG.
Infantry Tank Mk II A12 (Matilda II) - 24 tons, 25 kph, front armour 78 mm. 40mm gun + 1 MG.
Matilda I and Matilda II infantry tanks
139 of the Mk I tank were in service at the outbreak of war, and saw combat in France in 1940. However, their pitifully slow speed and lack of armament meant they were largely ineffective, though their armour was a nasty shock to the Germans since it was impervious to their standard anti-tank weapons.
The Mk II tank was designed to overcome the shortcomings of the Mk I. However, delays to production mean that none were actually in service at the outbreak of war, although a total of 3000 were produced in 1940-43 and saw combat in France and North Africa. The Matilda proved an effective tank at first, its armour being superior to most other tanks in service in the first half of the war; but its slow speed, unreliability and comparatively weak armament made it obsolete by 1942.
In addition, the Mk III Valentine tank was designed privately by Vickers - using existing components from their other tank models - and offered to the War Office on a commercial basis. It was not yet in production at the time war broke out. The Valentine was not quite as good in combat as the Matilda, but was smaller, much more reliable, and far cheaper and easier to produce. As a result it became the British tank manufactured in the largest numbers during WW2, with 6900 being made in the UK and another 1400 in Canada. Many of these were sent to the Soviet Union as lend-lease; by Soviet standards it was only a light tank, but it was valued for its reliability.
Cruiser Tanks
Cruiser Mk I A9 - 11 tons, 42 kph, front armour 14mm, 40mm gun + 3 MGs.
Cruiser Mk II A10 - 12 tons, 27 kph, front armour 30mm, 40mm gun + 1 MG (Mark IIA has 2 MGs).
Cruiser Mk III A13 - 14 tons, 50 kph, front armour 14mm, 40mm gun + 1 MG.
Cruiser Tanks Mk I, II and III
The Mk I was designed by Vickers in 1937, entering service early in 1939. 125 were built. However its thin armour was quickly seen as a shortcoming, and the Mk II was hastily designed as a replacement, cutting out two machine guns in order to save weight for thicker armour. Even so, the Mk II's speed of 27 kph was barely faster than the infantry tank. 175 were produced.
The Mk III was designed by Nuffield, one of the new companies brought into tank production. It used the revolutionary American Christie suspension , which allowed for significantly faster speed (at the price of being more bulky). 65 were built, but then it was decided to increase the armour along the same lines as the Mk I/Mk II upgrade. The Mk IV tank was the more heavily-armoured version (30mm frontal armour) , but none had yet entered service when war began.
Light Tanks
Light Tank Mk VI - 5 tons, 58 kph, front armour 14mm, 2 MGs.
Vickers Mark VI light tank, by far the most common tank in British service in 1939-40.
The latest in a series of Vickers designs ultimately based on the Carden-Loyd tankette, but with a radio and a rotating turret. The British army had a thousand of these at the outbreak of war, compared to fewer than 200 heavier tanks. However, during the Battle of France they were forced into front-line combat instead of the scouting and patrolling duties they were intended for, and suffered extremely heavy losses in consequence. This somewhat discredited the concept of the light tank in British eyes, and the Mark VI was not replaced (apart from a limited number of light tanks produced in WW2 for specialised roles such as glider landings).
And just as a contrast, here's the Centurion, which was just entering service in 1945 as the Germans surrendered. The first six Centurions were delivered to the British army in Germany before the end of the war, but they didn't actually see combat then (not until Korea).
52 tons, 35 kph, front armour 150mm, 76.2mm gun (17-pounder*) + MG. (Later upgraded to 105mm gun).
* Able to penetrate 208 mm of armour at 457 m. The German Tiger II's frontal armour was 185 mm.
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