How to spot a perfect fake: the world’s top art forgery detective

Like criminals of every stripe, modern forgers have kept easy pace with the techniques that attempt to trap them. Art forgeries have gotten so good – and so costly – that even Sotheby's, one of the world's largest brokers of fine art, has trouble weeding them out. Samanth Subramanian from the Guardian, tells us all about James Martin, the fraud-busting expert who Sotheby's brought in to spot these perfect fakes.