The 30-year-old singer told housemates Jasmine Waltz and Luisa Zissman that he has a close relationship with bisexual Duncan.
He said: “I work with Duncan, I go on holiday with Duncan, I live with Duncan.” Asked: “Do you have sex with Duncan?”, he replied: “Yeah all the time.”
And one person who Lee's revelation came as surprise to was his mum, Sheila, who says she had no idea he is/was bisexual.
“I had no idea that Lee was bisexual," she told heat. "But I think it’s fantastic that young people talking about their sexuality can be celebrated without fear of repercussions.
“Personally, I think he’s definitely more of a ladies’ man, but as a mummy I would support him in any choice he made in life,” she added.
Meanwhile, 'Apprentice' runner-up Luisa revealed she also has a soft spot for Blue star Duncan.
Luisa was with Lee and Jasmine in the 'CBB' bedroom when she said: “Duncan is so fit.”
“He’s gay,” Lee responded, about his bisexual pal, before Luisa continued: “But is he? He’s so attractive."
She then asked if Duncan had had any work done on his face: “But has he had his cheeks done, Lee? He’s so chiselled, so attractive.”