Has anyone ever fitted the no. plate boot lid repair panel on an HE xjs, I can weld and have experience in panel work but at £65 it seems like a good deal.

 

Can't help, I am afraid; but if I were doing it, I would build a complete jig for the entire boot lid - itself rather a task - to which all the required reference points were exactly made, so that the angle, depth etc etc if the panel was exactly as the original. Without that, I think it would be all too easy for the angle between the lid and the number plate panel to be incorrect, as well as the seals not to be right, etc etc.
Mind you, if you are flush, I saw an entire new NoS lid for sale recently on the usual auction site....

 

I've been looking on ebay and I resent paying shylocs £500 for something that jaguar were selling for £100 a few years back and, as you say, I think a jig would def. be necessary I may pass on this.