LONDON - FEBRUARY 04: Andy Warhol's 'Mao' is displayed at Christie's on February 4, 2008 in London. Christie's Post War and Contemporary Art Evening Sale takes place in London on February 6, 2008. Getty Images logo Getty Images 21 months ago

LONDON - FEBRUARY 04: Andy Warhol's 'Mao' is displayed at Christie's on February 4, 2008 in London. Christie's Post War and Contemporary Art Evening Sale takes place in London on February 6, 2008.