Well it managed 1800 miles, I had really thought Triumph had got it's act together after years spent riding the old Meriden bikes.
At least it's in my garage and not at the side of the road.
Looks like a clutch switch failure.
Well the update on the fault is that the wire from the starter switch had not been inserted correctly into the connecting plug under the tank, so had worked loose. apparently took four hours to repair, fairing and tank off.
Bike fine and a joy to ride