Yes, I obviously don't want to create ill-will or make things worse. Ownership of the land in question is clearly with our house, and there is a right of way through the entry. There is a tree on our bit of land, and parking just east of the tree does not obstruct the right of way, but equally, I do not believe that the right of way confers a right to park upon anyone else. The neighbour's problem is that he can't park on his side because that would obstruct the right of way, including to his own garage and parking space. He is the first house on his side, we are the second on our side. He's been using the first neighbours space on our side as well, and they clearly don't like it either, although I haven't discussed it with them - yet.
I have written and delivered by hand two letters asking him not to park on my land - he has not replied in writing. I told him when we spoke that I would take legal advice.