Tarquin1980

Hello - We have a neighbour who is being particularly difficult with an issue on our party wall. Our garages are linked at the front but at the back there is about a 30 cm gap. Both garages have a flat roof and on our side the rain water that collects flows off our roof a between the two walls. We have had 5/6 roofers round and they are say that they can run a gutter pipe to collect the water and run it round the back onto the rear of our garage. My neighbour insists that he doesn’t want this as it is “on his land”, it will be “an eyesore” etc. Where do we stand as we want to get this rectified ASAP. He is suggesting we have a drain installed on the flat roof and take the water out internally….any thoughts/ideas/suggestions?