The 'rent cheque' painting went under the hammer on 14 October

The artwork, created between 1973 and 1974 and given to the Royal College of Art in London in return for rent, had been expected to fetch up to �9m.

Study from the Human Body, Man Turning on the Light was sold by the College to raise funds for a new campus.

But other major works at this weekend's auction failed to sell - news that may cause disquiet in the art world.

Pieces by Andy Warhol and Jean-Michel Basquiat were among the unsold items, while several works by Damien Hirst were bought for below their pre-sale estimates.

This month's London auctions are being closely watched for signs that after several years of rising prices, the red-hot art market may be cooling.

So far the signals are mixed, with many works selling for solid, but unspectacular sums.

Record price

Bacon's picture was one of a series of studies of the male nude executed by the artist in the late 1960s and early 1970s.

Earlier this year, his Study from Innocent X fetched $52.6m (�26.5m) at Sotheby's in New York - a record auction price for a Bacon artwork.

Born in Ireland, Bacon became one of the most prominent contemporary artists of his lifetime despite having had no formal training.