I had a similar problem, checked with the Land Registry, and was told that there was no clear indication who owned it, but that it was a right of way, and nobody was entitled to block it. That would obviously include allowing access to it. Perhaps have a word with a Citizens Advice Bureau if you have one handy. If you can establish whether that situation applies, let your neighbours know. It sounds as if they're a nasty bunch. If there is unpleasantness, you can consult the council, but you may have to involve a solicitor.