The law says its trespass and he shouldn’t do it. However if he does and he ignores any warnings, then your remedy is an application to court for an injunction to stop him doing it again.
The potential problem for you is that unless this actually causes any damage or is common-law nuisance or an ordinary English dictionary definition of the word “nuisance” and it’s just annoying, whilst the court could grant the application against you it may not necessarily award legal costs.
It would be different if whatever he is leaning against the fence damages it or pushes it over.
It’s also different if he’s doing it to annoy you because that’s harassment.
It is often the case that a robustly worded letter from a/your solicitor threatening a court application and an application for costs, may resolve the issue without the need to go as far as court.
On your house insurance you may have legal expenses cover that would pay for the legal cost so it’s worthwhile checking. Some do and some don't.
You have probably seen a pop-up offering you the chance of a telephone call at an extra cost. It is up to you whether you have a telephone call or not but do bear in mind that a 15-30 minute telephone call covers an awful lot of ground and you can get an awful lot of information in that time. So you can ignore it or go ahead or go ahead later. It’s your choice.
Meanwhile, we can carry on on here.
Thank you for letting me assist you with your legal question. I am glad that I was able to help.
I am not certain whether that answers the question for you or not, but I am happy to answer any specific points arising from this.
It will be my pleasure to help you again either further with this or any future questions you have