I have come to the conclusion that the PO put the engine back together again in a hurry just to sell the car.
The Allen key needed to undo the grub screw is 1/4", and I had to buy a 1/4" key as I did not have one that fitted, so I am fairly confident that I did not remove that grub screw.
At least the answer was not expensive, just time consuming. When the engine was out, I found the clutch plate had stuck itself to the flywheel, the screw holding the speedo cable into the gearbox was not long enough to grip it so I fitted a longer one, and it gave me a chance to clean things that had corroded, so all of the time removing and refitting the gearbox and engine was not lost.
