WHEN polar explorer Ernest Shackleton handed a starving fellow traveller a biscuit on an expedition more than 100 years ago, his companion said he would not swap the morsel of food for ''thousands of pounds''.

Now one of the biscuits that nearly made it to the South Pole on Shackleton's Anglo-Irish Nimrod expedition was expected to sell for almost that amount at an auction in London overnight.

A Huntley and Palmers biscuit from Ernest Shackleton's Nimrod store is held by a Christie's employee. Credit:AFP

The biscuit, one of thousands that were the diet for Shackleton and his companions on the 1907-09 expedition, has a catalogue price of up to £1500 ($A2370), according to auctioneers Christie's.

Made especially for the expedition by British biscuit company Huntley and Palmers, the rations were fortified with milk protein to help the group on their arduous journey.