The issue with the Bob Semple Tank is that it wasn't actually a tank, it was an improvised fighting vehicle. I suspect one of the big issues was the fact that, lacking either a large calibre gun, or sufficient native machining capability to manufacture a turret ring, they went with a bloody stupid design that ought to have been scrapped even before it had been finished.
What I think might have worked fractionally better was a design akin to the WW1 Medium Mark A Whippet.