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
EastEnders Bianca Jackson and Tiffany Mitchell. Lock also wrote a character guide entitled "Who's Who in EastEnders" () in 2000, examining main characters from the first 15 years of the show. Show creators Julia Smith and Tony Holland also wrote a book about the show in 1987, entitled "EastEnders: The Inside Story" (), telling the story of how the show made it to screen. Two special anniversary books have been written about the show; "EastEnders: The First 10 Years: A Celebration" () by Colin Brake in 1995 and "EastEnders: 20 Years in Albert Square" () by Rupert Smith in 2005. EastEnders