Colourful tale of love, fortune and loss behind iconic art sale

It may set a new record price for a work of Chinese contemporary art when it goes under the hammer in London later today. Whatever unfolds in the auction room, however, Yue Minjun's Execution has already left an indelible mark on the lives of four people for whom the past decade has been coloured by the haunting work.

At the centre of the story behind the painting is Trevor Simon, now 36, who was a young investment banker in Hong Kong when he paid two-thirds of his annual salary in 1996 to buy Yue's masterpiece for HK$250,000, and less than a year later traded a half-share of it in return for an engagement ring.

Then there is the woman who walked away from her relationship with Mr Simon months after his proposal but kept the ring. There is also the Hong Kong diamond dealer whose share of the work of cynical realism inspired by the bloody Tiananmen Square crackdown may leave him several million US dollars richer by this evening.

Finally, there is the artist himself who, since painting Execution in 1995, has been elevated from dangerous subversive to officially endorsed celebrity and one of China's most celebrated contemporary artists. Yue's reputation is expected to be further enhanced by what happens at Sotheby's.

The fortunes of the four became intertwined when Mr Simon bought the painting from Hong Kong dealer Manfred Schoeni, who was murdered eight years later in a botched robbery in the Philippines. Schoeni sold the painting on the condition that it remain hidden from public view for five years because of its political sensitivity.

Mr Simon decided to propose to his American girlfriend, but having borrowed heavily to purchase Execution, he had nothing to fund his grand gesture except the painting itself.