Les,
I have asked CAPA for their input but I do not believe it failed due to one event ie the drags. There were no pieces of clutch in the bellhousing and I think it must have been slipping for some time.
In hindsight I did notice the take up point change at the time i had the dyno tune done. The clutch had only done a few hundred kilometers then. I put this down to bedding in but think that something may have happended then. Will never know.
So I think its been slipping and overheating for some time which led to failure of the facings.
I'll keep all informed .
Phil