An actress posing as a contestant from the Australian Big Brother has entered the reality show's UK house.
Actress Thaila Zucchi appeared in the ITV show StarStreet
Pauline, played by Thaila Zucchi, from Wiltshire, must stay in character in the house, but will be able speak as herself in the diary room.
The other contestants will win a luxury shopping budget if they blow her cover.
As part of "fake week", Friday's evictee will be returned to the house after their eviction interview, which will be seen by the other housemates.
Zucchi appeared in ITV series StarStreet, which was based on her band the Allstars, who scored four UK top 20 hits during their two-year career.
She must pretend that she has been evicted from the Australian version of Big Brother to be sent to the UK.
Pauline has her own luxury living area in the compound and will receive instructions from Big Brother via a special kangaroo-shaped telephone.
Housemate Charley Uchea voiced doubts about her authenticity, saying: "She ain't even been in Australia, she's probably been living in London and just picked up the Australian accent."
Fellow housemate Carole Vincent insisted: "She's Australian."
The contestants are also being led to believe that Welsh nanny Laura Williams, who was evicted on Friday night, has been sent to Australia to take Pauline's place.