Cheers prelude/ Andy.
Yes I told them to just repair the cylinder and replate, I read everything I could find on here relating to cylinders beforehand.
When I stripped both cylinders down neither one showed any signs of detonation which pleasantly surprised me. I’ve just got back in from the second heat cycle and it feels lovely and tight (it should do really) . I had the plugs out after the first heat cycle just to check that all was ok and again just now. It always has Esso super in it as well.
The only thing that puzzles me is why it let go in the first place, I’ve been through and checked every thing and it’s all spot on.

Once again this forum has been a huge help and source of knowledge so thanks for taking the time and effort to do it Andy.

Chris.