David, when I had mine done earlier this year, the chap setting it stated that there was a band rather than a single setting in which the rear wheel should be, mind you he was talking fractions of a degree so it must be a fairly small band.
I used Nottingham Car 4 Wheel Alighnment Ltd (snappy name!
), they were very good, and cost about £50 including adjustment to front and rear. It was a full laser set up and included a print out of the before and after settings. Tyre wear at the back now seems even, and the niggling pull to the near side has dissappeared.