Mr Hirst's former girlfriend Joanne Staniforth dug out the original oil portrait of her sister Julie's cat Mindy – created and signed by the teenage artist in 1982 – when his collection of 223 works smashed Picasso's record for a single artist auction.

Trademark death-themed exhibits by the controversial artist include pickled animals and a severed cow head being eaten by flies.

Joanne, of Cavendish Avenue, Pontefract, said: "Damien painted Mindy for Julie, she absolutely adored her cat and loved the picture so kept it for years.

"Three years ago London auction house Sotheby's couldn't value the painting as it wasn't in his usual style.

"But to Julie the painting is priceless and we've had lots of interest.

"If she was offered a ridiculous, life-changing amount of money then she would consider selling."

A £10m bull floating in formaldehyde was the most lucrative lot at Mr Hirst's Beautiful Inside My Head Forever auction in Sotheby's on September 15.

Mr Hirst, 43, was brought up in Leeds and went to Leeds College of Art and Design before studying fine art at Goldsmiths, University of London.

Hairdresser Joanne, 43, added: "We met at school in Leeds and split up three weeks before my 18th birthday when he wanted to be young, free and single.

"I wasn't surprised he became famous because he was the sort of person you knew would make it whatever he did."

A spokesman for Sotheby's said they did not comment on art not in residence at the auction house.