Here is a short report that was found by a friend of the site while archive digging on “Estimation of the Chances of Defeating Enemy A.F.Vs. with British Tank and Anti-Tank Guns” created by Armor Operation Research Group. No date is included in the report, but it is reasonable to assume it was written during the latter part of WW2. This report was photographed quickly by hand, so please excuse the quality of the pictures. It is probably best not to take the figures provided in this report as gospel since the report clearly states that it is providing estimates, not test results. To quote the report itself:
The estimates have little meaning as isolated absolute values and are to be interpreted on a comparative basis only. Even with this proviso they are not fully reliable owing to paucity of information regarding such subjects as German armour performance and behavior of capped shot at high angles of attack. It is pointed out in particular that the estimates probably tend to overvalue gun performances at longer ranges, owing to the method us for assessing accuracy of fire, and that they are not sufficiently reliable for fine comparisons to be drawn between performances of A.P. and A.P.C.B.C. shot of the same calibre.
That said, the report is interesting as it shows what the British Army assumed was the effectiveness of their tank and anti-tank weapons versus late war German armor.