Finally had an annoying knocking sound coming from the rear nearside of the ST fixed today! Took it to a well known Ford dealer in Dagenham and the techy there was very good, took him out for a spin, listened, got it up in the air, pulled on something and straight away found it. Apparently it was the suspension linkage arm that had failed! Thought I'd share in case anyone else found other knocks/rattles in the same area as this seems pretty common.
They also offered to change the power steering pump which has been recalled and I got them to respray the front bumper as its lost some lacquer and I had only bought the car last week. What a result, their also going to give it another exterior valet.
Very pleased with the service, considering another garage in the same chain couldn't find anything wrong and handed me back the keys with little explanation of what they had actually done.
Now it's time to spend some money and get it DCSIed up!!