Well the Matilda was kind of a special case. It was small (volume) for it's weight. It was a bit easier (not a lot easier) to transport than a larger tank of the same weight. Still needs the same bridging equipment. The Matilda only gained it's reputation because of it's armor for the most part. It carried a bit less ammo than the Cruiser tanks. You also need a bigger hull to fit in a bigger powerplant if you want a faster tank and the increased hull size is going to run up weight quick.
On Matilda II, the powerplant was not very volume and weight efficient because of the twinned up engines and the transfer case to combine the outputs. I'm not sure if the Soviet figures are actually true, but you could actually fit the Churchill's Bedford engine in a smaller volume than the twinned up Matilda setup, and even the former is not all that efficient so there is even greater room to improve.
Keep the 2pdr, Keep the basic A 13. work on fixing the existing Liberty and not start dissipating design and development work on 3 different bespoke tank engines, while trying to sort out the modified Liberty.
For the A 13, add more armor, add 5 wheel if needed.
Get the Centaur/Cromwell into production sooner. Maybe by killing the Covenanter on the drawing board. And perhaps a few other projects.
Just get the tank guys and the gun guys to talk to each other sooner. A close to Comet with the 77mm in production at the end of 1943?
Put a sloped nose on it instead of the left over Cromwell nose.
Considering that Covenanter and Crusader only existed to squeeze a Light and a Heavy Cruiser into a 18 ton weight limit, you could get away with indeed just improving the A13 Mk II somewhat while working on the 1938/39 A13/A15 within a 25 ton limit (or at least slightly in excess of 20 tonnes), ideally accounting for the incoming 6 pdr and a proper new engine.
Especially when they use single skin construction and a slightly higher weight budget (greater than Crusader Mk III), you can absolutely obtain Cruisers with the same frontal protection as a Valentine but without the drawbacks. In general with a slightly higher weight limit and better design you could absolutely run the Cruisers with balanced protection, moblity and firepower in 1940 already.
The curse of the British Cruisers was that they kept only increasing design weights (and design load capacity for the springs) incrementally instead of leaping to new weight categories in one go. 13-14 tons with A13, 16 tons with Covenanter, 18-19 tons with Crusader and Covenanter III, 21-25 tonnes with Cavalier and early A27, 28-30 tonnes with late A27, A28, and Heavy Cromwell Stage I, 32-35 tonnes with the A31, A32, A35 and Heavy Cromwell Stage II, and up to and beyond 40 tons with A36, A37 and A40.
Ideally, one could do with A13, 1940 generation Cruiser (25 ton limit chronological stand-in for Crusader/Covenanter), 30-ton (or more) Cruiser (A27 or ideally something closer to A34 Comet from the start, A30), 35-40-or 45 ton Cruiser (A37/Centurion stand in). Ideally going for a significant weight increase with A27/34 stand in would allow the immediate use of the armor schemes developped for Heavy Cromwell Stage I, A28-31-32, eg 3.5, 4 or 4.5 inches.
Of note that A37 and other late projects used a special external variant of Christie suspension which allows single-skin sides, and the mount for that suspension was stronger to handle the heavier weight. Another remark is that most Christie suspension setups require cross tubes on the bottom of the hull which take a similar space as torsion bar suspension. You could actually get away with using TB suspension on British and other Christie tanks with next to no height penalty, but a sizeable gain in space and available width no longer taken by the springs. And some weight savings. Incidentally the French AMX-40 did use external Christie suspension.
Cross tubes seen here on the floor of this A30 Avenger.
External Christie on the AMX-40 sitting between the hull and the roadwheel and side skirts, efficiently fitting over the wheel support which already requires width.
And the French souped-up 47mm tank gun still wasn't as good as the British 40mm.
Yes, at least once APC(BC) was introduced on 2pdr. (Also
tomo pauk
) The 590 m/s MV would refer to the HE round on 47 SA 35, the real comparison would be between 47 SA 34 and 47 SA 35 which shot the antitank projectile at 450 and 660-680 m/s respectively.
For some reason everybody thinks the standard British 6pdr was a bad gun. It was being designed in 1938, it was test fired in 1939. It should have gone into production in late 1940 or early 1941 and most British service tanks in 1942 should have had the 6pdr in late winter/early Spring of 1942, not just showing up in the late fall of 1942.
It was definitely the best sub-75mm gun of WW2. Ironically, the British were the 2nd country after France to actually field heavily armored tanks (A11 and A12), with the USSR not far behind.
If an underfunded British tank program could do this, then the British should have accounted for the enemy being able to field at least equally armored tanks, requiring appropriate ammunition for the 2 pdr and ideally a more powerful gun even if only as part of a 2-tier system (just like France with 25 and HV 47mm).
Again as an analogy to the French, the latter tested 25, 37 and 47mm projectiles (capped, with or without BC) against 20, 40, 47 (sloped), 50, 60, 75, 80, 90 and 100mm cemented or homogenous plates just in the year of 1936. Since 1934 already they were looking at engaging thick (T/D of 1 or greater), sometimes cemented plates which is why they exclusively used solid shot APC(BC) on all new guns below 75mm caliber (here they worked on capped APHE). Difficult targets will often break up the solid shot projectile anyway which makes a bursting charge less relevant.
Many countries instead expected just the bulletproof or 30mm-thick-or-less armor schemes of the 1930s and 1940 and used APHE, often without an AP cap. But due to the bolded bit above, there should have been good reason to start developping 2pdr ammo of similar construction to the French projectiles from 1934 onwards when A11 was mooted. Had the Director of Artillery been allocated the ressources needed to proceed with 6pdr at a less constrained pace and schedule, it could have been in production in 1940 already with both the towed carriage and tank mount and turret figured out. This would be enough.
As you noted, HE should also be available for 2 and 6pdr from the start regardless of their value, both are already a little better off than respectively 37 and 47/50mm calibers in terms of possible payloads. Additionally, early development of APCBC and HE (almost from the start) would also allow tanks to be designed accordingly around longer ammo than the plain AP and no HE that the guns started with. Historically this created issues with ammo stowage when new ammo types were introduced.
Same issue with 17 pdr historically as well (no APC and APCBC at the start) which created issues for the A30 Challenger which was well in development before the ammo types were devised.
Please note that the French 75 was NOT semi-automatic even though it was "quick firing" weapon. It depended on a gunner's hand to operated the handle to open and close the Breech. US/British tank cannon could fire French 75mm ammo but the tank guns had new breech blocks (they also had new barrels).
Of note that the French 75mm tank guns with mle.97 ballistics (the aptly-named 75mm "Self-Propelled Type") were derived from the mle.1929 casemate gun with a new barrel and a new sliding breech. Automatic at that, eg the breech closed automatically when the round was rammed in by the spring-operated mechanized rammer to reduce the loader's work .