The standard British and CW anti-tank gun was the 40mm 2 pdr. This gun did not have a HE shell. I was thinking about the US 37mm M3, as it DID offer a HE shell. Could this gun be used in the British or CW supply chain? Did Britain or the CW use this gun at all? For example, did British Grant tanks used this gun? The Grant served in India and Burma, so they must have had a supply of shells.
Would the M3 gun fit into the smaller British 2-pdr tank turrets like on the Matilda and Valentine?
From an Alt History POV, would the M3 gun offer any advantage to the British tanks.
Now, a caveat, what I am not asking for is a debate on should the 2 pdr have a HE shell. Such a shell was not designed until 1942/43, when the 2-pdr was essentially obsolete. Instead, I'd like to focus on the opportunity to install the M3 gun into British tanks in 1939 onwards to provide a HE option.
Looking at the M3 ammunition where we see the HE details, the most interesting projectile IMO is the canister shot,
https://en.wikipedia.org/wiki/37_mm_Gun_M3#Ammunition It would be useful against
Bansai charges.