[Jools]

If there is definitely a clonking from the front end you might also want to check that your wheelbearings are sound, after all, wheelbearings go a lot more often than headrace bearings unless you make a habit of badly landed wheelies. Clonks and clanks are always difficult to trace because they get transmitted through the frame.

You might also want to consider checking out the rear end. The symptoms that you describe are exactly how my bike felt on the two occasions that my rear wheel bearings were on the way out and the rear wheel was steering itself.

Oh yeah...forgot to say that when you do the 'hold front brakes on and compress forks' you get a clunky clicking noise like you describe from the brakes...they all do that sir...