I was asked to replace all the door handles in someone's 1970s bungalow.

They had nasty brass lever handles and had bought a load of stainless steel lever handles from BQ.

I discovered that the square metal shafts linking the handles of the new ones were a tiny bit bigger than the square holes in the tubular latches on the doors and had to replace all the latches too. The shafts fitted the new latches perfectly.

Were latches made with smaller holes in the 70s - is this some kind of imperial V metric thing?