Liz, can't you point them towards the Register of Electors they keep at the Town Hall? If he ain't on your registration there, I reckon you've got a watertight case that he doesn't live with you?

Or maybe see a Commissioner for Oaths and swear that he's not resident at your address - they'd surely have to take notice of that? Would cost you, but it would be better than harrassment from the bailiffs?

Hope that one of them works!
S:0)