I recently picked up a small strange cast steel item. It is 2" long and square in cross section, but of different widths. What looks like the drive end is approx. 11/16" and 5/8" long with a 1/8" collar on two sides. on the other end are two square sections one marked 3/4, but actually 9/16", the other marked 1/2, actually slightly over 3/8". It might be some kind of plug remover, but the receiver for the 3/4 would have to be deep enough to take the 1/2. It is marked 'Pemberthy', which sounds English.
Any ideas?
CP