In our part of the world(nw uk) a Birmingham screwdriver is another name for a hammer, a few reasons why this might be but I don't know the definitive reason. A very interesting thread, how about a bit more non British slang. Some slang gets futher modified around here, for instance a 'cowboy' (builder, pumber,engineer etc) meaning someone who cuts corners resulting in a poorly finished job, is often refered to as a 'hickock' as in Wild Bill.