Abi Harper, played by Siobhan Hayes, first appears in series 3 as the daughter of Ben's cousin Richard (Anthony Head).
In the 2005 Christmas special Alfie Butts (Rhodri Meilir), a friend of Nick's, moves into the Harper household.
In most episodes he can be found trying to come up with ingenious plans to annoy his wife, get rid of his kids and sit on the sofa with a beer and the paper.
He enjoys watching football (shown supporting both Arsenal and QPR) and reading Tom Clancy, although it usually takes him the better part of a year to get through a single book.
His children each have their different problems, possibly due to the chronic lack of attention from their dad who doesn't seem to care about anyone.
This lack of tolerance is shown to others outside of his family too, mainly towards his dental practice partner Roger Bailey.
Susan Beryl Harper (née Riggs), MBE, is a tour guide, and later works in an art gallery.
In the same series, she had to deal with Janey moving to Manchester to go to university, and Nick flying the nest to live in his own flat.
When the family appeared on Weakest Link, Grace revealed that Susan had a one-day marriage in 1973, after she married a wrestler called Troy the Punisher in Las Vegas while drunk.
Nicolas "Nick" Harper (born 15 June 1980) is the oldest child of Ben and Susan, the older brother of Janey and Michael and the uncle of Kenzo.
Nick has attempted many jobs, such as a female impersonator, stunt-man, stripper, magician, landlord and exorcist but was hopelessly unsuccessful at all of them.
Kris Marshall left at the end of series 4 as he had grown tired with portraying an immature character much younger than his actual age.
She develops a bad headache when she goes without sexual intercourse for more than two weeks at a time: this causes her to become very aroused and to chase after any man she sees.
Michael Harper is Ben and Susan's unplanned third and youngest child,[4] the younger brother of Nick and Janey and the uncle of Kenzo.
At the start of the show Michael was a typical 'geek' who is highly intelligent if sometimes naive, and exhibits a strong sense of morality and integrity, attempting to win the election for student president as a conservative or "Tory" by honest means.
He then tells them that he has been in a relationship with a man for some time, a 25-year-old solicitor called Scott Marsh, who later moves into the Harper residence.
Michael is later seen in gay clubs picking up men and giving out his number, suggesting that he and Scott have broken up, but they later get back together.
[4] Roger is frequently depicted as childlike, simple-minded, cheerful and enthusiastic, serving as a direct contrast to Ben.
Abigail Therese Bernarde "Abi" Bailey (née Harper; born 1979) is Ben's first cousin once removed.
Although good natured, Abi is very accident-prone, especially in the earlier series, where she puts her hand through a window, and hits Ben around the head with a cricket bat, thinking he is an intruder.
She is a Catholic, and, in the final episode of series 8, she becomes a nun, and opts to stay with her order rather than to return home with Roger.