Parapet wall ingress from neighbour

[Gas man]

Hi there I have been having some slow water ingress that’s causing some mold to form. The cause appears to be be damp coming through the parapet wall between myself and my nighbours house. We both had extensions at the same time, but where I used a builder he did his himself, but he did use a professional roofer for his roof. My neighbour is an extremely difficult person to deal with, and He insisted on building the shared parapet wall so I have no comeback to my builders on this and I even paid another roofing coming to redo the part of my roof that is by the parapet to ensure it’s not that as my nighbour was claiming it’s my roof that’s at fault. I have photos of where it appears to be coming through from his side. The houses step down on the street hill and My side is covered in lead to the top but as his house is lower he has much more walk to cover and so has a lot of bare brick showing. can I have some opinions on if this is any good? To me the wall looks like it should be rendered or wrapped. The wall stays soaked even when there’s been no rain for days and only ever looks dry in summer. This has been going on 2 years so any advice is appreciated. P.s the worst of the damp appears to start where the cement is on the left where the roof pitch comes down

 

[mrrusty]

The lead's wrong on the pitched section. I'll leave it to the professional roofers to tell you why.

 

[catlad]

Does it have any soakers between the slates?

 

[Gas man]

The lead's wrong on the pitched section. I'll leave it to the professional roofers to tell you why.

Thanks but I failed to mention iv had 3 roofers look and not point anything out that’s why im trying here to see if I can get anywhere

 

[Gas man]

Does it have any soakers between the slates?

Sorry but I have no idea as it’s my nighbours roof and he refused to acknowledge the issue