I think a Cromwell IV would be a great addition to the GV set.
A British tank would be a welcome introduction.
I believe it to have been quite fast with a powerful 75mm gun (HE & AP)
It looks like it would sit well among the M4s, and Panzers. However, it may be slightly more vulnerable due to it's vertical armour.
It was use extensively by the British 8th Army. (Desert Rats) during the invasion of Germany 1945.