Sorry not to get back right way been away . Bikeman spot on I think. I swopped my backwheel and no problems! The old wheel was a dura ace 9speed hub which I believe should work fine with 10 speed (but didn't!) Have a ultegra 10speed hub now with the 10 speed cassette.

Thankyou everyone for info/comments and shall now go and see if I can isolate that squeak! Blimey! Always something.

m