Tenant wants to change the tenancy agreement

That student tenant upstairs has suddenly got it in his mind that he want to change the tenancy agreement. Apparently his girlfriend has suddenly got a whim that she wants to try her hand at independent living and wants to move into his room.

I've said no. I've said to the student tenant that the tenancy agreement clearly states that the room is let to him and know one else. I don't want any of that student hanky panky shinanigans going on under my roof.

I've read my rights. I know that if I wanted to change the rent I couldn't without getting his agreement or by serving a section 13 notice on him.

Therefore I don't see why I should let him indulge in his carnal fantasies.

Mrs Jones has a very strict rule of no sex before marriage, something that of course I support very strongly. I wonder what she would look like....without her bedsocks, jumpers and dressing gown.....