Thanks for your response.
I agree that the Coping stones are part of the wall as they primarily protect the wall from rain / damp etc and will advise him of this.
My neighbor is insisting that I am responsible for the roof as I had the loft conversion done.
I have pointed out that I have already paid for the complete roof to be replaced, so all the roof tiles, roof felt and ridge tiles. The concrete render and flashing was also repaired on both parapet walls. As I understand it we are jointly responsible for the external wall as we are semi detached and the neighbor on the left side should be partly responsible for repairs to the party wall/ parapet wall.
Th coping stones requiring repair are all on top our external wall.
I have read through the terms of the lease and the external walls and roof are mentioned, but nothing as specific as the coping stones.
I have also approached my neighbor and suggested we get a variation to the lease to clarify the situation regards the roof and loft space, but he has not understood and has been reluctant to co-operate.
Can I have a variation to the lease drawn up and present it to him and if he does not object within say 28 days then the variation is considered to be valid and accepted?
I have also paid a builder to carry out repairs to the coping stones and asked my neighbor to pay 1/3 of the outstanding balance on completion of the work.
I feel I have bent over backwards to facilitate the work and maintain good relations with my neighbor and builder, but am now running out of patience and options.
Thanks again for your advice.