Started assembling the clutch, fitted the oil pump gear and new idler gear and circlips. Fitted the clutch basket and hub then started checking all the plates, which were all within normal tolerances, the metal plates had some blueing, so I gave them a gentle blast to clean up the surfaces followed by a throughout clean.
I took the clutch plates out as a pack and on inspecting them found there were two friction plates next to one another without a metal plate in between, so the clutch must have slipped all the time. Also the bearing in the outer plate was shot so wating for a new one of those to arrive.