In article ,
"mlv" writes:
I've tried all the obvious suppliers without success and I guess I now need
to find an old-fashioned hardware shop that still closes on a Wednesday
afternoon.

If you're anywhere near Fleet, Hampshire, then Bakers in the main
shopping road (Fleet Road) is one of the few left. Just don't come
on a Wednesday afternoon (and I'm not joking;-)

--
Andrew Gabriel