Russell T. Davies originally wanted Christopher Eccleston for Stuart Alan Jones after seeing Our Friends in the North (1996). Eccleston auditioned, but ultimately declined the role, saying he felt he was "too old" for the part. When he withdrew, he recommended they audition Aidan Gillen. Ecclestone did work with Davies on The Second Coming (2003) and the first season of Doctor Who (2005).
Vince is a Doctor Who (1963) fan. Both Russell T. Davies and script editor Matt Jones are also fans and wrote spin-off novels for Virgin Publishing in the mid-1990s. Davies later became executive producer of Doctor Who (2005) and hired Jones to write The Impossible Planet (2006)/The Satan Pit (2006).
A follow-up, spin-off series ("Misfits") was initially commissioned by Channel 4 due to the show's success. It would have followed the characters of Hazel, Alexander and Bernard from the original series, while introducing new characters. Although Russell T. Davies developed draft scripts for four episodes and storylines for a further 22, the series was cancelled before it went into production.
Constant Craving (1999) and Married... with Children (1999) were originally to have been written by another writer. However, when early drafts proved unsatisfactory, the writer was fired and Russell T. Davies elected to write the entire series himself. As a result of this, the episodes were written after That's What Friends Are For (1999) (but before Crimes of the Heart (1999)) and were somewhat lacking in plot. Davies has never revealed which writer let them down.
The role of Alexander was written for Phil Collinson, a good friend of writer and creator Russell T. Davies. However when Antony Cotton arrived for the audition, everyone agreed that he was better suited to the role. Collinson went on to be a producer, and was hired by Davies to produce Doctor Who (2005).