The bike is now up and running again

The problem was quite simple to fix; only needed a screwdriver and an Allen key to get at the screw. The screw holding the plate stopper onto the gear shift drum - No 21 in the diagram – had worked loose.
Simple, eh? Thanks to Andy750 for this solution.
At least I now know that my clutch is in OK and goor for another 10K at least.
I’m off towards Canada - Belfast, Ontario tomorrow, and a new blog post will be coming soon, soon; promise.
Sean