I like how this is progressing. The shape is workmanlike and practical against the backstory, so bravo.
This has got me thinking about the Cromwell and what would have happened if development of the 6 Pounder had been followed through further. It is documented that the 6 Pdr could out penetrate the 75mm against armout, the lack of viable HE shell holding it back.
Slightly different turret shape, longer 6 Pounder.. hmmm.. do I have a Cromwell still in the stash ?