Hello I am a solicitor with 20 years experience. How can I help you with this. You son of course has a right to play in his garden, I a not sure what information you are looking for? It sounds to me like your son may have been the victim of an assault.
So what can I do to stop this man coming close to my children again. If it is a public right of way, but he assaulted my son can I stop him from coming through?