Neighbours Extension Roof Overhang

What are my rights in this situation.
Neighbours extension roof overhang. Neighbours have extended their house by putting a conservatory concerned as the gutter overhangs into our property. This is unlawful unless you have given permission. You do not specify what the building is i am presuming it is an extension on their property. A further problem i noticed is that the neighbour s flat roof and fascia overhangs the boundary and their flat roof is also at an unusually steep angle.
If a person s extension goes over the boundary by a few inches the neighbour or the neighbour s successor if the house is sold cannot just turn round a year or so later and demand it be removed. If your neighbour refuses to cut their roof back so that it is within their boundary your only option would be to take them to court although there is a possibility that the courts will say that 3 inches is too small a trespass to make a ruling on. Your neighbour s overhanging roof is a simple matter of encroachment. I have spoken to my neighbour twice over recent months asking him to reposition his shed in order to alleviate the problem but to no avail.
Let s say the neighbour took the issue to court and he could prove the tresspass and could prove that the builder had not acquired specific rights by easement. Neighbours guttering overhangs my property how do i prevent my neighbour putting the gutter from his new building over my boundary. My neighbour has a shed in his garden the roof of which overhangs my fence and the rain runs off directly onto the fence and supporting fence post causing it to rot out.