A photograph of a mysterious footprint believed to be that of a yeti has sold for £3,500.

A Christie's auction in London, themed on exploration and travel, included Captain Lawrence Oates' sleeping bag case from his ill-fated South Pole expedition with Captain Scott in 1912.

A 1951 image of a footprint

The 'yeti' footprint was photographed in the Menlung Basin in the Himalayas in 1951.

A team of mountaineers travelled to the region on a reconnaissance mission before attempting to conquer Everest for the first time, a feat achieved two years later.

A member of the expedition, Tom Bourdillon, sent it to his friend Michael Davies with an inscription on the reverse.

"Dear Mick, here are the footprint photos: sorry for the delay. We came across them on a high pass on the Nepal-Tibet watershed during the 1951 Everest expedition.

"They seemed to have come over a secondary pass at about 19,500ft, down to 19,000ft where we first saw them, and then went on down the glacier. We followed them for the better part of a mile.

"What it is, I don't know, but I am quite clear that it is no animal known to live in the Himalaya, and that it is big. Compare the depths to which it and Mike Ward (no featherweight) have broken into the snow. Yours, Tom Bourdillon."

Christie's spokesman Matthew Paton said: "There has been a great excitement over the yeti photograph. It trails a history of 20th century exploration in the Himalayas and we were very glad to see it go for more than twice its estimate."

The yeti was first sighted in 1925 by N A Tomaz, a member of the Royal Geographic Society, while on an expedition in the Himalayas.

A debate was sparked over the creature's existence, and several exploratory expeditions, but no conclusive evidence of the animal's existence has yet been found.