She lies, legs spread wide and one breast exposed, in a pose that — for all the accomplishment of the artist — fails to convey what is so utterly fascinating about the beguiling model Henrietta Moraes. 

She was the legendary Fifties beauty who sat, or more properly reclined, for the Francis Bacon portrait — described as 'sexually charged' by Christie's — which sold to an unknown buyer for a staggering £21 million in London this week, far exceeding its guide price

That makes it one of the most valuable of the painter's works, tripling as it does the price achieved by another Bacon portrait of Moraes, entitled Lying Figure With Hypodermic Syringe, that was sold a couple of years ago. This featured the model in the grip of a heroin trip, and Henrietta Moraes's extraordinary story only adds to the picture's notoriety.