Lady Gaga has said she thought her fiance Michael Polansky was joking when he proposed to her on April Fool’s Day.

The American singer and actress, 38, said she had wanted to keep the engagement “a secret”, but was heard on video at the Paris Olympics earlier this year introducing entrepreneur and investor Polansky as her fiance.

In a recent interview with US Vogue, Gaga said that her mother, Cynthia Germanotta, had set them up after meeting Polansky through philanthropic work.

A woman with short red hair and a check top
Lady Gaga said she though Michael Polansky was joking (Matt Crossick/PA)

She told The Graham Norton Show: “He proposed on April 1 and I thought he was joking.

“Then when we went to the Olympics, we were filmed saying hello to the Prime Minister and I was caught on camera saying, ‘This is my fiance’. I had wanted to keep it a secret.”

Gaga, who performed at the games’ opening ceremony, also spoke about her latest acting role, playing Harley Quinn, the love interest of the Joker in Todd Phillips’ Joker: Folie a Deux.

She said: “I tried to root her in reality and create Arthur’s love match.”

The film, which is the sequel to the 2019 movie Joker and whose title refers to the French term for “madness of two”, is a musical fantasia which follows Arthur Fleck, known as The Joker, and Quinn, as they fall in love at Gotham City’s Arkham Asylum.

They are known for their toxic romantic relationship in the comics, and trailers for the film show Phoenix and Gaga singing and dancing together

The Born This Way singer said of recording all the music live: “Joaquin (Phoenix) did not like it at first, which was hard, but he did it and was phenomenal. It was really fun and interesting to do and watching it back it may be the most vulnerable singing I have ever done.”

Having recently announced a 13-track “companion” album to the film, named Harlequin, she said: “It is all original production but inspired by the character. She cannot be defined and the songs reflect that.”

A woman ina check dress and a woman in a black jacket with a very small dog
Lady Gaga, Demi Moore and Demi Moore’s dog Pilaf (Matt Crossick/PA)

Also on the show is American actress Demi Moore, with her dog, Pilaf.

The actress, 61, spoke about her latest film, body-horror The Substance, in which she plays a fading Hollywood beauty who turns back time with a new drug.

She said: “It is almost impossible to fully describe because it is dealing with some serious subject matters.

“The best way I can sum it up is that it is like The Picture of Dorian Gray meets Death Becomes Her meets a Jane Fonda workout video.”

Graham Norton stands behind two women and three men who are sitting on a sofa
Lady Gaga, Demi Moore, Colin Farrell, Richard Ayoade, Jack Savoretti and host Graham Norton (Matt Crossick/PA)

Irish actor Colin Farrell talks about his latest stint in the Batman spin-off series The Penguin.

He said: “It is a huge relief now that it is out and people think it is all right. If you are shallow and insecure like me, you are expecting a slap in the face so a rub on the back is definitely preferable.”

Farrell wears heavy prosthetics, which he said made him “a bit miserable and angry”.

Comedian and actor Richard Ayoade promotes his new book and Jack Savoretti and Miles Kane perform on the show.

The Graham Norton Show is on BBC One on September 27 at 10.40pm and is also available on BBC iPlayer.