X Factor contestant Rylan Clark and Jockey Frankie Dettori went into the Celebrity Big Brother house and immediately had to banish half their housemates to the basement. Bosses on the Channel 5 show have decided to make life hard for some of the contestants, with half spending their time in the grotty basement area, where there is no running water, no windows and residents will have to scavenge for food from the scraps from the main house.

Told their task by Big Brother in the Diary Room, Dettori and Clark looked distinctly uncomfortable but said: "Somebody's got to do it." As the other housemates were introduced in pairs by host Brian Dowling, Dettori and Clark had to decide who would go the luxury house, and who to the basement. They first sent model Paula Hamilton to the basement as being more irritating than actress Tricia Penrose, who was allowed to go to the house proper. Ms Hamilton took it well, but laughed bitterly when she saw conditions in the basement, saying: "Oh my God, charming, delicious, oh, now I feel at home."

Heidi Montag arriving at the launch of Celebrity Big Brother. Credit: Ian West/PA Wire

She added: "We're are all in this together" - which was daubed on the wall. Next Dettori and Clark had to decide who was more "fake" out of Neighbours actor Ryan Maloney, who has played Toadfish in the Australian soap since 1995, and ex-EastEnders and Footballers Wives star Gillian Taylforth, and sent Maloney to the basement. He said: "I'm up for a challenge, bring it on." In the basement he and Hamilton heard an announcement about a champagne reception upstairs. Hamilton said: "We're in the sin bin."

Former football Neil Ruddock says he has 'history' with Frankie Dettori. Credit: Channel 5/PA Wire

And Maloney added: "It looks like we'll be here all night."Rylan Clark has been installed as favourite to win the show by bookmaker William Hill, with Dettori next. One absentee is comedian Jim Davidson who had been due to appear but was dropped after being arrested and questioned by detectives over allegations of sexual offences, which he denies.The contestants will spend the next few days holed up in the custom-built property in full glare of TV cameras with a winner emerging later this month if they can prove popular enough with viewers and their own housemates. The series is expected to last three weeks, with the first eviction due on Wednesday.

Host Brian Dowling (left) introduced Frankie Dettori as the house's first celebrity. Credit: Ian West/PA Wire
  • Lacey Banghard, 20. The glamour girl from Bedford won the Page 3 Idol competition before going on to model for Nuts, Front and Loaded as well as appearing as a Soccer AM Soccerette with ex-CBB housemate Rhian Sugden.

  • Claire Richards, 35. She signed up with pop group Steps when she was still a teenager and toured the world selling millions of records.

  • Frankie Dettori, 42. Born in Milan, he moved to England as a teenager and became one of the most successful jockeys of his generation.

  • Gillian Taylforth, 57. Played Kathy Beale in EastEnders for more than a decade where she was involved in dramatic storylines including several affairs, rape and death.

  • Neil Ruddock, 44. His football career was defined as an uncompromising hardman in defence for teams including Millwall, Liverpool and Tottenham Hotspur.

  • Paula Hamilton, 50. Starred in a 1980s advert for Volkswagen where she left her husband, ditched her jewellery and fur coat but kept the car.

  • Rylan Clark, 24. His theatrical style made him a hit on last year's X Factor. He has also had a stint in a Spanish boyband and in Take That and Westlife tribute acts.

  • Ryan Maloney, 33. The actor, who grew up in Melbourne, has played Jarrod Toadfish Rebecchi in Neighbours since 1995.

  • Sam Robertson, 27. The Dundee-born model and actor rose to fame playing Adam Barlow in Coronation Street and has also appeared in River City and Beaver Falls.

  • Tricia Penrose, 42. Appeared in ITV drama Heartbeat as well as The Royal and Emmerdale.

  • Heidi Montag and Spencer Pratt, 26 and 29. Featured in US TV show The Hills, with their relationship repeatedly dominating the storylines of the MTV series.

Dettori enters the house just weeks after he was given a six-month ban from his sport after a positive drugs test, which he said had left him feeling "ashamed and embarrassed".

"It doesn't matter what I took or how much - what I can say is it didn't make me ride any better or make my horse run any faster," the Italian-born showman said after the ban, which followed a positive test in Paris in September.