Is all property theft? Apparently so, sometimes

I probably shouldn't write about this, but since only two of you are reading it I'll take the risk. I was hanging out at the house last Wednesday, chewing the fat with the painters, as you do, when a man came to the front gate waving a sheaf of papers and asking to come in. There was something about the papers that made me unwilling to open up so we talked through the railings. He was the son of the now deceased owner of the house next door, and he wanted me to know that the house was being sold and that the new owner had been apprised of the possibility that a part of our garden actually belongs to his house. In an oddly affable way, considering what he was asking of me, he said that he just wanted me to sign an 'accord' about this, though without explaining what precisely he wanted me to agree to. Since obviously I'm not in accord with the notion that my garden is actually his I wasn't about to sign anything. I told him to get his lawyer to write to us and refused to discuss it any further, although I agreed to let him have my mobile number.

On Friday night, in the lobby of a cinema in London, my mobile goes. It's the new owner of the house, just ringing to let me know that he still thinks my garden is his but he's going to be nice and let my children carrying on playing in it. Just so long as he can access his garden through my garden whenever he needs to. He insists, and I agree with him, that the most important things is that we have good neighbourly relations, and he isn't going to do anything to jeopardise (I've tried spelling this four different ways, all wrong apparently) this, just so long as I recognise that it's really his garden and he's being a real gentleman about this. I tell him, as nicely as I can (I have a bit of problem which is that I can do really nice and really mean but I struggle with anything in between) that I don't think he has a claim on my garden but I appreciate the sentiment.

Yesterday I visited the service d'urbanisme of the commune to find out more. A nice woman shows me the website of the cadastraux, which is the French land registry and shows the boundaries of every plot of land. It is not quite the final say, in that it can be disputed, but according to our notaire, it's generally recognised to be the official map of your terrain. Nonetheless, according to the woman I spoke to at the cadastraux, it has no legal weight, it's entirely topographical...Still, reassuringly, it clearly shows that our garden belongs to our house and not to his. Last night he calls. I tell him that I've been to the cadastraux, that it unequivocally shows that the terrain belongs to us, and that he needs to stop bothering us about it. He tells me that he has some fifty year old plans that show that there used to be a wall there and that at that time that bit of garden belonged to his house. I ask him what happened in the interim, when and why the wall got moved and why it's not registered as still belonging to him. Then I asked him straight, does he want this land. He says no. I ask him in that case why he's pursuing it, if he doesn't even want it. As far as I can tell, officially it's ours and will remain so unless he brings a land surveyor in - as he tells me he is planning to do -who can prove that the cadastraux are wrong.

Somehow this feels like a feud straight out of Balzac. He just wants to be friends. I just want my garden. And yet he isn't going to let it rest.