The 34-year-old singer, who is openly bisexual, quipped that after a brief fling with the 33-year-old star he realised that he was interested in men.
Talking to her band mate Tony Lundon, Michelle revealed that she and Duncan had once spent the night together.
She said: “Me and Duncan had relations.”
Duncan later joked: “Me and Michelle had a little thing... she turned me gay.”
We’re not sure it quite works like that.
The singer then went on to describe the struggles he went through coming to terms with his sexuality before coming out in 2009.He explained: “Being brought up a strict Catholic, being gay was wrong.... Being in the band, being around other gay guys, kind of made me realise it was OK.
“I had a secret undercover relationship with one of my dancers and I couldn't tell anybody. I couldn't tell anyone.
“I went about 3 years of not telling anybody. I was confused. I was still sleeping with girls.
“He was heartbroken. He couldn't be with me anymore. It was when he was gone out of my life, I realised who I was.”
Meanwhile during last night’s eventful episode, Kerry Katona continued to struggle with life as part of Atomic Kitten again.
After finding out that she would be wearing a black jumpsuit while her band mates Liz and Natasha would be wearing skirts for their comeback performance, Kerry threw a wobbly.
She told the gig’s producer: “I look like a binman.”
What glamorous bin men do you have working down your street Kerry?
The 32-year-old singer then complained that the outfit made her look like a lesbian.
She explained: “I know I've got a shaved head... but I look like a lesbian in it. Not that there's anything wrong with being a lesbian. I just don't want to look like one.”
[Related article: Blue get a frosty reception on joining The Big Reunion]