Does actually feel like a crossed thread, but I cant see it being as
it goes on dead straight. I went into B&Q with the tap today and
found one flexible tap connector which screwed on perfectly, but all
the others (which appeared identical) stopped after about a turn just
like the nuts on the bath pipes. I asked the assistant in there
hoping he might help but he just reckoned I shouldn't worry about the
resistance and tighten it up - I havent tried this yet.


I personnally would go with this suggestion, if the taps are UK
manufacture,
supply etc. then they 'SHOULD' be standard 3/4" thread. You can do a
couple
of things first though. Try tigtening some connector to the taps whilst
they are not connected to the bath, this way it will be easier to see what
your doing and also to undo them later, have you tried lubricating the
threads with something like Vasalene (sp?) first to help the threads
tighten
up.

I was being too cautious - I just expected to parallel threads to go up and
down easily (by hand). Doing it up with a spanner has worked and doesnt seem
to have destroyed the threads in the process )