As I am getting on a bit. I do not relish laying on a roof and trying
to get ivy of the wall below. I will probably have to pay somebody.


Looks as if the only solution is for you to continue your pruning of the
ivy. Most householders with gardens experience an invasion of
vegetation from their neighbour's gardens and this is inevitable.
Mostly it is dealt with by chopping it off at the boundary line and
there the matter rests.

Regards,
Emrys Davies.