LONDON (Reuters) - An unfinished portrait of Francis Bacon by Lucian Freud, one of only two he ever painted of his friend and the only one whose whereabouts is known, sold for 5.4 million pounds on Sunday, auction house Christie's said.
The 85-year-old Freud's only other picture of his fellow artist Bacon, painted in 1952, was stolen from a show in Berlin in 1988 and has never been seen since in public.
The two men, among the greatest post-war British artists, were firm friends. While Freud, who is regarded as one of the world's greatest living artists, frequently sat for Bacon the latter, who died in 1992, returned the favor for only two portraits.
The unfinished portrait dates from 1956/7 and as with the missing painting it shows Bacon with downcast eyes.
The two men sat knee-to-knee for the painting before Bacon left abruptly, it is thought to pursue his lover Peter Lacy in Tangiers, Morocco.
"The present work offers a fascinating snapshot into the working methods of the artist at a critical point of his artistic development," said Christie's in a statement.
"Freud had begun to work in a more expansive way using thicker brushstrokes, liberating the paint and creating a more worked complexion, more seasoned and full of life."
Estimated to sell for between five and seven million pounds, the picture has been the property of the current owner since 1972 and has only rarely been seen in public -- in 2002/3 and 2005.
In May Bacon's "Triptych, 1976" sold for $86 million setting a record for postwar art, while the day before that sale Freud's "Benefits Supervisor Sleeping" established a new mark for a living artist when it sold for $33.64 million.
Reporting by John Joseph; Editing Matthew Jones