May 16 (Bloomberg) -- A 1967 Francis Bacon painting of his male lover will go on the auction block July 1 at Sotheby's in London as the British painter's work appreciates like an Internet stock in 1999.

Sotheby's has assigned a presale estimate above 8 million pounds ($15.6 million) for ``Study for Head of George Dyer.'' On May 13, Christie's International sold Bacon's ``Three Studies for Self-Portrait'' for $28 million in New York. It fetched $2.9 million nine years earlier.

The next day, an undisclosed telephone bidder purchased Bacon's celadon-green three-panel ``Triptych, 1976'' at Sotheby's in New York for $86.3 million, the most expensive contemporary artwork ever sold at auction.

``We wanted to build on the momentum of the triptych,'' Oliver Barker, a senior specialist in contemporary art at Sotheby's in London, said in a telephone interview.

Dyer grew up in East London and served short prison terms for petty crime. He met Bacon in a Soho drinking den in 1963, according to Sotheby's, and they were together for eight years. In late 1971, they traveled to Paris for a retrospective of Bacon's work. Shortly before the opening, Dyer was found dead from an apparent overdose of sleeping pills. Bacon died in 1992.

Daniel Craig, of James Bond fame, played Dyer (opposite Derek Jacobi) in the 1998 film ``Love Is the Devil: Study for a Portrait of Francis Bacon.''

The Bacon sale is part of Sotheby's evening contemporary art auction in London and comes as the Tate Britain prepares a Bacon exhibition, opening in September. Sotheby's said in a statement that the portrait had been in a private collection for 40 years.

To contact the reporter on this story: Philip Boroff in New York at pboroff@bloomberg.net.

Last Updated: May 16, 2008 00:01 EDT