In uk.d-i-y David Lang wrote:
Hi Chris
The tap is very likely indeed to have a standard thread, no matter
how old (well, at least 1/2 a century). If the plastic connector
goes on without splitting or the threads being chewed up, that's
not the problem.

Dead right. All threaded taps are BSP threads, even in Europe. In 30 years
of connecting pressure washers to taps I've never found a domestic tap that
wasn't 3/4" BSP.

Well as I said earlier in the thread I have come across hose fittings
which are nearly, but not quite, 3/4" BSP. Not the taps themselves
but intermediate bits which *should* have been able to interface with
standard 3/4" but wouldn't. On inspection it was obvious that the
thread pitch was slightly different.

--
Chris Green