Just a flight of fancy, I came up with the idea of creating a heavy self-propelled gun for the Royal Artillery of World War II. Maybe I need to get out more, I dunno...
The Friar, continuing the Commonwealth penchant for ecclesiastical artillery names, would just be a Valentine Mark I hull minus its turret with a BL 7.2" gun-howitzer mounted on the back. The only difference between the two versions would be that the Mark I utilised the original short-barrelled Mark I-Mark V guns that were re-lined WWI 8" howitzers; while the Mark II would mount the new-build Mark 6 that was roughly 2 metres longer. Far from being a perfect fit, this wartime kludge would of course suffer reliability problems but in my personal head canon, the Friar would remain in service until the M110 came along in the mid-60s, simply due to a lack of any alternative weapon system.