Billy Mitchell (EastEnders) revealed in 2006 that the role was extended by "coincidence and chance": "I was offered four episodes and here I am, about 800 later. [...] Ross Kemp (Grant) said that he was leaving, and there was a gap in the Mitchell family, so they brought me back to do stuff towards his leaving. After that they offered me a year." Billy was reintroduced in 1999, making recurring appearances. He was involved in the leaving storyline of Grant Mitchell in October 1999, before returning later in the year as a regular character. When Billy was first introduced, he was depicted as
Sam Mitchell (EastEnders) for storylines that are certain to intrigue our viewers." The character made her return on-screen on 22 July 1999 and was involved in the storyline relating to actor Ross Kemp's departure, and romances with her brothers' enemies Beppe di Marco (Michael Greco) and Steve Owen (Martin Kemp). Despite Westbrook's claims that her close friend Mike Reid had backed her decision to return, he and other "EastEnders" actors later publicly denounced the BBC's decision in a documentary about Westbrook, as they had first hand experience of Westbrook's addiction on set and were concerned for her welfare. It was reported that Westbrook