The mask went under the hammer in Bonhams Book, Map and Manuscript sale in Knightsbridge, London, yesterday. It had been estimated at 40,000-60,000 pounds.
The cast - known as the 'Boys cast' - was made for the Rev Richard Boys, Senior Chaplain of St Helena, shortly after Napoleon's death on the island of St Helena on May 5, 1821.
It was the most significant example remaining in private hands and bears an autograph note of authentication written by Boys. All but one of the other examples are in national collections, either in France or in Corsica.
After Napoleon's death, there was a protracted wrangle over whether his physician, Francesco Antommarchi, or the British doctor, Francis Burton, should make a death mask. Practical difficulties also meant that this was not done until 7 May, two days after the former Emperor had died.
The mask was given to the Rev Richard Boys by the portrait painter, JW Rubidge, who assisted Antommarchi in making the mask. Boys received it before Napoleon's entourage left the island towards the end of May.
"Before the invention of photography, taking a cast from a person's face was the one way of producing what may be described as an objective likeness. These masks were most often taken after death," said Felix Pryor, a consultant in Bonhams Book, Map and Manuscript Department.
"The present death mask of Napoleon can be seen as standing at the end of this long tradition - the world's first photograph was to be taken only five years later," Pryor said.
