A series of security blunders allowed a lone thief to pull off one of the biggest art heists in history, in May 2010. Five masterpieces by artists including Picasso and Matisse – worth up to £ 430 million – were stolen from the Paris Museum of Modern Art.

But officials admitted that during the raid a £ 15 million alarm system was broken, and had been for three months, guards were said to be ‘dozing’ and external CCTV cameras were all focused on the museum roof. With the alarm out of action, the intruder was able to slip into the museum by removing a window on the ground floor, where he was not recorded by the ineffective outside CCTV.

He then spent 15 minutes inside, where three guards were said to have inexplicably missed him as he was filmed by an array of cameras. Investigators believe the staff may have been taking a nap. The crime was not discovered until 7 a.m., three hours after the intruder made his getaway.