The show was produced by Baby Cow Productions for BBC Wales. It ran for a total of 21 episodes, broadcast from 13 May 2007 to 25 December 2019, comprising three series and two Christmas specials. Initially, the series was shown on channel BBC Three, but a growing following meant that it was subsequently moved to BBC One. The last episodes of the final series formed a significant part of the prime time BBC seasonal programming, and were broadcast on Christmas Day 2009 and New Year's Day 2010. In May 2019, it was confirmed that a new episode was to be created for Christmas Day 2019 and written by James Corden and Ruth Jones.
