David, Tom's carrier is a Canadian MkI (*) U.C. and Michael R's screen frames and screens are original. It would be the British ones which (early on at least) were slightly thinner. I believe the frames are the same for practical purposes. The hole sizes vary, the shapes vary, the radius on the rounded ends of the flat steel varies, the distance from the ends that the holes are varies
I do agree however, that 10mm thick perspex will be difficult to fit in a 5.5mm slot.