That 37mm AT gun was quite a handy little weapon all thanks to the good sense of providing it with a H.E. shell, unlike the 40mm 2 Pdr. which had better sights but too high a profile and not even a canister round, let alone H.E.
The shop stewards of the Royal Artillery weren't going to have those AT guns getting out of their place by firing H.E. shells, most improper!Except of course it was no laughing matter at the time.
Strikingly small trunnion. The gun captain's hand must be on those binoculars somewhere...