Bacon work due to fetch up to £6m

An employee at Christie's admires the Francis Bacon painting

A portrait by Francis Bacon bought for £31,500 in 1971 is expected to fetch up to £6m when it goes under the hammer in London next month.

Man In Blue VI is one of seven paintings in a series the artist produced in the spring of 1954.

The work, which has been exhibited internationally, depicts an ordinary figure in the middle of a dark void, representing anxiety and torment.

The painting will go on sale at Christie's on 11 February.

'Dreadful disease'

Bacon was one of the last century's most successful artists, earning about £14m before his death in 1992.

Man In Blue VI was painted during a period when he was in the middle of a violent and tempestuous relationship with Peter Lacy, a former Spitfire pilot.

Bacon called Lacy the great love of his life, but said his obsession with his partner was "like having some dreadful disease".

Their relationship was punctuated by fights that often resulted in Bacon's canvases being vandalised.

In early 1954, the artist moved out of their shared cottage into the Imperial Hotel at Henley-on-Thames, where he painted the Man In Blue series.

Experts believe the unknown subject was painted while visiting Bacon - who usually worked from photographs.

The work is expected to fetch £4 million and £6 million.

Man In Blue VII, the final picture in the series, sold for £707,750 at auction in 2002.