Ford Focus high pitched squeal

I have had a squeal on the car that has got progressively worse, so have had the alternator belt checked out today. Belt seems fine and garage has suggested that it could be one of the pulley's that could be squealing rather than the belt. They think it is likely to be the "jockey". They suggested speaking to a ford dealership garage to see if they know of a recurring problem on any of the other "focus" pulley's before they change the jockey or it could be a case of trial and error. Anyone have any experience of this squeal being anything other than the jockey ?