Following widespread media attention involving racism during the fifth series, the show was not broadcast the following year. The show returned in 2009, and the final series to air on Channel 4 aired in 2010. Following the show's move to Channel 5, Celebrity Big Brother began airing two series per year. The show has also had various other spin-off series occur since its premiere. The first spin-off, Teen Big Brother: The Experiment, premiered on 13 October 2003 and lasted for a total of ten days. The series was met with much controversy, which was later heightened when two of the cast members had sex in the house. Big Brother Panto, which aired in 2004, saw the return of ten former housemates who re-enacted their rendition of Cinderella. Ultimate Big Brother was the final series to air on Channel 4, and featured fourteen of the most memorable housemates from both the main series and Celebrity Big Brother competing in the series. Brian Dowling became the only housemate to win a series twice after winning Ultimate Big Brother. Numerous other spin-offs have occurred throughout the series such as Big Brother's Big Mouth, presented by Russell Brand, and Big Brother's Little Brother presented by Dermot O'Leary. Following the show's move to Channel 5, Big Brother's Bit on the Side and Celebrity Big Brother were the only spin-off series now airing. Format Big Brother was a game show in which a group of contestants, referred to as housemates, live in isolation from the outside world in a custom built "house", constantly under video surveillance. During their time in the house, the housemates are required to nominate two of their fellow contestants for potential eviction, and the two or more with the most votes would be nominated. This process is mandatory for all housemates, and failure to comply could result in expulsion from the house. During the show's broadcast on Channel 4, the viewers would vote to evict one of the nominated housemates, and the housemate with the most votes would be removed from the house. The twelfth and thirteenth series, the first two to air under Channel 5, saw the public voting to save a housemate, and the housemate with the fewest votes would be evicted. Beginning with the fourteenth series, the vote to evict format returned to the series. During the eighteenth series, both vote to save and vote to evict were used.