Alfie Butts is a friend of Nick Harper's who turns up at the door of Ben and Susan's house. He says that Nick had invited him over. Susan then lets Alfie stay as a lodger much to Ben's disapproval. Alfie then becomes a main character of the sitcom.
It is later found out in series 9 that Alfie was not invited by Nick and infact a post card from Nick in the household states 'not to let Alfie in and stay'.
His final appearance is the finale of season 9, Kenzo's Project'.