Well, finally I have a date to have the broken windscreen replaced, Saturday............ and then Sam reminded me that I still had the noise to look at first.
So, this afternoon I jacked the car up, popped the wheel and drum off to have a look and discovered the remains of a stud in the bottom of the drum assembly........
Closer inspection revealed one stud missing which holds the hub/backplate assembly to the trailing arm..... whoops!! Slightly important stud then!
I tried to put a new stud in, but as I suspected the thread has gone in the trailing arm. The proper fix would be to strip it down and helicoil the trailing arm.......... but I just don't have time to do that before Saturday morning when its got to be at the windscreen place in Worcester by 9am................. I found a long bolt the right size and it was just long enough to catch the remains of the thread at the end............ then I checked the other 5 and they are all still tight, so that'll do for the moment!