Where were the neighbours, his friends' parents, his mother's friends?
Please, if you are concerned about a child, report it. Otherwise this will keep happening.
The agencies responsible for safeguarding are Health, the Police and Social Care (not Education - all schools can do is the same as the public, pass on their concerns).
Call 101, the NSPCC or your local council's children's services if you are worried about a child. If the abuse is happening there and then, call 999. If it keeps happening, keep calling. If you, as an adult, are scared of the person causing the abuse, then think how the child must feel and make that call.