People will take liberties if they are not aware of boundaries. Had a problem with a young neighbour years ago, who decided he was going to plant shrubs down the side of my drive. I said 'Oh no you are not'. 'Its my lawn', he said. This is why the problem arose...because we are open plan frontages, and although it looks like his lawn, my boundary ran in a straight line from the corner of his house to the pavement. This meant a 3 foot strip of lawn belonged to me. Luckily I had the drawings to prove my freehold.
The only reason he wanted to plant stuff was because when I worked on the side of the car, I used to lay a wheel on the grass and sit on it. So I made sure I kept those papers here, and indeed many years later, my new neighbour said he was going to remove the adjoining rear fence and put a new one up, I showed him my paperwork, and said you can put a fence up, but you leave mine as it is, and put yours on your property. I explained that any fence erected on the original boundary, no matter who by, was my responsibility to repair if it fell down. They did erect a 6' fence on their property, and a few years later, it fell down. Again, the next new neighbours asked me if I was going to repair or replace it, as it was leaning into their lawn, and that fence was my responsibility. I again showed the paperwork, and said if he looked over the fence, he would see the original 3' ranch fence on my property. Problems all solved without any fuss or ill feeling (except for the first young snotty upstart who had his nose put out of joint)