I have lived in my house for getting on 40 years. Our wonderful (and sadly now ex) next-door neighbours bought the house on the attached side of our semi-detached house in 2012.
There was a lot of work for them to do, including sorting out the front garden which was in a mess. We had a drive on ours, albeit not in the best of condition, so when the neighbours told us they were getting a driveway installed too (this was about 2014) we asked if we could go in with them and have ours re-done at the same time, using the same contractors.
Our neighbours also had plans to install a footpath from the proposed drive, across the section of grass that would remain, to the their front door & side access. We liked these plans, and asked for the same. Our neighbours organised everything, and we paid for all of the work that took place on our side.
The work was done, and we ended up with one continuous driveway across the two properties, and matching footpaths from the drive to our respective front doors. The dropped kerb runs all the way from my side to theirs (It's the size of 2x double dropped kerb).
Soon after, the neighbours installed a 4ft fence all around the three sides of their grassed area of the front garden, with a gate leading to their new footpath. We did not desire a fence, so did not duplicate this on our side.
However, in the middle of our two properties, up against the house and on the boundary, there is a soakaway drain with a waste pipe from the guttering that runs across the front of the roofs of both our houses. Although the drain is in the middle and on the boundary, there is more of it on our neigbours side than ours.
Because of this, when the neighbours had their fence installed, they went about 20 inches from the boundary on their side, so that all of the drain was on my side of their fence, as doing it the other way so that the drain was in their side meant having their fence over my side of the boundary. In other words, we gained about 20 inches of the grassed area of their front garden.
This was their choice, and for all the years they lived there, life was very good. Sadly, they moved about three months ago.
Today I bumped into the man who has bought the house (it's a family but we've seen very little of them). He was pleasant enough, but mentioned that he's aware that we have part of their garden and that in the new year he plans to see about taking it back. I told him we have absolutely no issue with this what so ever, and that we'd never asked for the fence to be put where it was, so if he wanted to move it, that was up to him.
But then he said it was our responsibility to get this done, at the least pay for it! He said he'd checked the deeds and that the boundary is ours to maintain (this is correct, as we went through all of this 10+ years ago when getting the driveway done) and therefore I would need to meet the cost of the fence being moved to what he calls the "correct" position.
I told him that even though we are responsible on the deeds for the boundary, there is nothing that says we have to have a fence, and nothing that says if one is fitted that I have to maintain it. I pointed out that in an estate of over 100 houses, there are only two with fences round the front gardens, and that having his fence installed was a choice that the previous owners made, not me.
It is further complicated by the fact that the drive is one continuous section, with no distinction between their and ours - ultimately, two cars can park side -by-side on each side (so effectively four cars in a row across two properties) and as our neighours had two cars (same as we do) we only ever parked on our respective sides, leaving plenty of room between our car and theirs. It's never been a problem.
My question is this - what (if anything) do I need to do now? And what action can my new neigbour take over a fence which has nothing to do with me at all?
Diagram attached - the red section is the 3-sided fence which I speak of, and the yellow rectangle between the two houses is the drain that sits mostly over their side of the boundary. The thick purple line is the boundary, and the thick orange line is the end of the drive where it meets the public footpath.
TIA.