One of the most controversial works of art of the last 20 years is going under the hammer when Tracey Emin's unmade bed is expected to sell for more than £1 million at auction.

The work, called My Bed, caused a stir when it was shortlisted for the 1999 Turner Prize although Emin eventually lost out to artist-turned-film director Steve McQueen.

The unmade bed, littered with condoms, cigarette packets and underwear, divided the critics but began the process that saw her become one of the country's most famous artists.

It was later sold to multimillionaire art dealer Charles Saatchi, who is selling it at Christie's in King Street, London, on July 1.

It is being sold with an estimate of £800,000 to £1.2million and all the proceeds from the item will help subsidise free entry at the Saatchi gallery and its free education programme for schools.

Emin, who first caught the public eye in 1997 with a drunken appearance on a television discussion show, was a leading light of the group dubbed the Young British Artists (YBA).

She has recently spoken out in support of the Conservative Party and described herself as "actually quite old-fashioned".

She said: "I love fun and I am notorious for throwing a good party, but I think at my age there should be some decorum.

"I don't think I will be celebrating many more. I want to ease down from that sort of thing and concentrate on my work. If that is going well, everything else falls into place. I am not married, I don't have children, I am totally financially independent and all I want to do is enjoy my work, which gives me the ultimate pleasure in life."