Station was so old (Kincardine 1960s) all the pyro installed was imperial sizes. All the new pots and glands in the stores were metric. So you can imagine the fun we had when ever there was a steam leak
I wanted some imperial ends a couple of years ago. I rang BICC and a very nice man sent me what I wanted f.o.c. !!!! also sent me a comparison / conversion chart...wish I could find it now. It is only usually the pots that are the problem [I believe they are a twin start thread] Glands you can just drill out with care [and a few spares to hand] I've still got plenty of imperial ends, and sometimes still use them!!!