Thanks again for all the comments regarding my last minute hitch with the tree commission.

I think I may have found an answer, which might be of use to everyone at some stage, especially combined with insurance.
Check out www.smartwater.com

I won't try to explain it as their site will do a better job - but apparently many insurers over here will ONLY insure valuable metals (even lead on church roofs) if this system has been used.

I'm waiting for the people to come back to me after Easter with more details.

Have a good weekend everyone.
Will