Now that's useful Kev, mine has a knock which on occasions seems to come from the front but then sometimes sounds to the rear. One thing I have found that when driving slowly (walking speed) and rotating the steering wheel from side to side I can get it to knock. The knock isn't there all the time just intermittent and not especially when cornering but when going straight. Think I will have to get it up in the air and have a look at the upper control arm. Are they particularly difficult to fit for someone reasonably mechanically minded?