Right, some progress.
Whole weekend spent on the car and now it's all in pieces. I think it was the clutch, but of course the proof will be when it all goes back together.
How the pressure plate should be attached (spare pressure plate):
How mine was (not) attached:
Would have fitted a new clutch but found the steel coolant pipe into the back of the block leaking, so need an O-ring.
Also spotted my DIS pack falling apart, so whilst gearbox off thought it would be a good idea to replace this. Was it f*uck! Even with the gearbox off it was a nightmare. My torx 3/8" drive was too fat to reach the bolts, one was increadibly hard to reach, then my 8mm socket (instead of torx) fell off under the DIS pack. Found another imperial socket that would fit, eventually found a way to get a purchase, then the bolt sheared. It had rusted solid into the DIS pack and captive nut at the bottom. Still at least I could lift the remains of the DIS pack off the remains of the bolt.
So car in pieces and friend who helped me lift the gearbox off back to Cambridge.
Need the parts, then help to get it back together.....