Whilst the British Army was the first to field tanks during WW1 and helped pioneer the way for other nations’ tank development in the late 20s and early 30s, it is quite clear that they had dropped the ball by the outbreak of war, having several different types of tank, of which none were particularly good.

The A9 and A10 Cruisers were the first of a long line of such vehicles, fast, lightly armoured, and well armed. However, they were highly flawed designs. The A9 Cruiser Mk.I was extraordinarily poorly armoured, with armour maxing out at a measly 14mm and its armament layout was as outdated as its armour was thin, being equipped with two secondary MG turrets, meaning it had a crew count of 6. The A10 Cruiser Mk.II eliminated these two problems, but subsequently came with its own set of issues. Its armour was twice as thick, though still only being 30mm, and this increase in armour came at the cost of a painful reduction in speed, clocking in at a blistering 26km/h, compared to the Mk.I’s 40.

Meanwhile, for the Infantry tanks, there was Matilda I and II. The Matilda I, being only armed with, at best, a single Vickers .50cal, was barely effective as a tank, with its only saving grace being an immense 60mm of all-round armour. Matilda II however, was a much more sensible design, and by far superior in every possible way. It featured the tried and tested 2-Pdr gun, a 3-man turret, thicker armour, and was twice as fast to boot, achieving a speed of upto 26km/h. The Matilda II was still slow however, its twin-engine setup was both complex and underpowered, the suspension was finicky, and the gun (while a perfectly good Anti-Tank gun) was very poor at supporting infantry, if units even received HE shells in the first place.

Back to the Cruiser side of developments, Christie suspension was making waves through British tank design departments, and would become a mainstay for Britain until the end of the war, surviving through eight generations of Cruiser tanks. For the British, their first Christie Cruiser was the A13 Cruiser Mk.III, while once again cursed with armour just about strong enough to keep out a bad storm, it now had a powerful but temperamental Nuffield-Liberty engine and a high speed of 50km/h to compensate. The Cruiser Mk.IV partially remedied the armour issue by (once again) bumping it up to 30mm, though this time it didn’t lose half of its speed in the process. For once, Britain had a tank that was both fast and competently designed. The Cruiser Mk.IV came rather late however, starting production in late 1939, and although it was a mild success, it was still held back by poor armour, lack of an effective HE shell, and an engine that threw temper tantrums every so often, it was clear a new tank would soon be needed.

Source(s) & Further Reading:
Wikipedia - Cruiser Mk.I
Wikipedia - Cruiser Mk.II
Wikipedia - Cruiser Mk.III
Wikipedia - Cruiser Mk.IV
Wikipedia - Matilda I
Wikipedia - Matilda II
Tank Archives - The First Cruiser (Cruiser Mk.I)
Tank Archives - With Best Intentions (Cruiser Mk.II)
Tank Archives - Playing Catch Up
Tank Archives - Britain’s Christie (Cruiser Mk.III)
Tank Archives - A Bit More Armour (Cruiser Mk.IV)
Tank-AFV.com - British Tanks