I live on a ground floor flat and completed an extension about 12 months ago. All party wall, building control, planning permission all granted and building completed to permissions. I built on the party wall as agreed with previous owner as they said that they wanted to mirror my extension and it would make sense to build on the boundary line and they would use that same wall once they start their extension.
However, neighbour's budget didn't allow the works (I know as they appt the same architect I used and he declined the work given the modest budget) and so the neighbour sold last summer and moved two weeks ago.
I encountered new neighbour two days ago standing on the boundary line looking at this new wall. I didnt know who they were and as I was on a work conference call was gesturing to my DC to go outside to see what they wanted. DC couldn't walk out what I was telling them to do, so I abruptly ended my call and went outside to speak to neighbour.
The person then aggressively accused me of shooing them away, which I explained I was gesturing to DC to go outside. And then the second sentence was that I had built on their land.
I proceeded to explain as above and they seemed to have been appeased and even invited me in for a tea.
The next day NDN had builders in who began hacking at the plaster on the party wall and putting in a damp proof course at 7.30. This wall is in my bedroom.
I called NDN at 10 to ask why she hadn't notified of works given party wall needed NDS picked up the phone with 'what do you want, and you've built on my land, I'm going to make your life hell', before I could even say anything.
NDN's upstairs flat is rented and the tenants have caused noise nuisance with domestic violence at 4 am waking my upstairs neigbour, myself and the previous NDN. Those tenants have been arrested, have had parties throughout covid. It would appear that previous owner (who reported to police, owner and council) did not disclose these details to new owner but perhaps mentioned they had issues with me - easier to complain about innocous issues ie: my DC practising musical instruments, she gave me times that they could practise and I appeased to keep the peace).
By the end of the phone conversation I had managed to explain that perhaps we had gotten on the wrong foot but I was not the neighbour that they should be having issues with, but the ones upstairs. They were quite taken aback and asked whether that was the reason why previous neighbour had moved.
So am I unreasonable one or NDN?
How do I move forward from this, I imagine having them next door will not be easy given that they are wanting to do extensive refurbishments and will need to go through planning. I imagine I will be bullied throughout.