Background
I'm sure, no matter what you model in WW2, you've heard of the British 17-pounder, most notably in the Sherman “Firefly’'. Well, there was also a towed version – however, it wasn't the most mobile piece, so the British looked for a way to create an SP gun. Fortunately, they avoided cloning the Bishop and instead came up with a new design based on the existing Valentine tank. To keep it compact, the gun faced over the rear deck in a rather low and sleek fighting compartment. The disadvantage of this layout is, of course, that one can't fire on the move, but it is great for ambush scenarios where you back into a firing position, crank off a few, and scoot away, and that ultimately became the fighting doctrine for this weapon.