My Speedy has developed a very bad front end wobble, if you take one hand off the bars it shakes violently from side to side?

I have looked over the bike on the hoist and can't "see" the problem.

Front wheel spins free and true.
Brakes are not binding.
Shockies appear to be functioning normally.
Balance weights are intact on the wheel.
No abnormal wear on the tyre.
Tyre pressure good.

Can anybody give me a clue where to look? It has been getting progressively worse and is more noticeable with a pillion on...

Regards.......Binnsy