OK, took the camshaft cover off and the flywheel plug out to check the timing.
The camshaft was only 1 tooth ahead of the crank pulley and the injector pump six teeth ahead of the cam pulley, so lucky us! Seems like no damage to the valves........so why was this......well, when the aux belt tensioner disintegrated one rib of the aux belt was stripped off and got wrapped around the back of the torsion damper and then dragged into the crankshaft cambelt pulley, spun around and chewed up disintegrated and sent around the other pulleys so no wonder a few teeth were skipped.
This is what I found behind the torsion damper

This shows the smeg behind the torsion damper, the plastic cover looks thick with grease, but its not, the plastic is scored and melted, I guess by the shredded aux belt!

This shows shredded bits squished into the cambelt teeth.

This shows a scuffed belt tooth where it has slipped.

This shows a piece of aux belt stuck in the cambelt idler pulley.

This is that piece pulled out, you can see the imprint of the cambelt teeth in it!

We thought that the previous owner had put a five rib aux belt on, the new one we put on was six, clearly the old one was a six rib, but 1 and a half ribs had been shredded off. So It looks like we got off lightly, a good clean up, new cambelt and tensioner & re-time and away we go. Will be next weekend now so will let you know how it goes then.