毕加索、达芬奇、安迪·沃霍尔、肖恩·格林哈尔希……肖恩是谁？肖恩·格林哈尔希可是艺术界的知名人物，不过艺术界宁愿忘记他才好，因为他伪造并销售仿真度极高的艺术品长达17年之久才被警方逮捕。

On 17 November 2007 a man was jailed for producing works of art. Why? Because the sculptures and artefacts Shaun Greenhalgh made were fakes: fakes that had conned museums and galleries out of over £500,000.

Shaun had left school with no qualifications, but tried his hand at a wide range of crafts – from watercolour painting to sculpture. The young Greenhalgh hoped to make it as an artist himself. His pieces were not admired, however, and he turned to forgery. He ended up creating a cottage industry in his garden shed, with the help of his family.

If the son had a talent for art, his father, George, had the gift of the gab and approached potential buyers. He came up with detailed stories about how he found artworks which had been lost for generations. In 2003, they sold a 50cm statue called the 'Amarna Princess' to Bolton Museum. George claimed his own grandfather had bought it at an auction in 1892 at an aristocrat's home, and had papers which appeared to back up his story.

After talking to art experts, the museum paid more than £400,000 for the statue. The successful scam made the forgers grow bolder. But when they approached the British Museum with some more fake artefacts, an expert spotted mistakes and tipped off the police.

After 18 months of investigations, the police knocked at the family's door. They were surprised by the Greenhalgh's humble home. Where were the riches of successful criminals? The police concluded that Shaun was motivated by "a resentment of the art market" and by a desire to deceive art experts, rather than by money.

But how did he manage to fool so many experts? Irvin Finkel from the British Museum says the family produced things that "in a way we were looking for already". So when experts saw them they wanted to embrace these apparently long-lost treasures.