'Le Mystère Picasso' is a remarkable documentary film made by French director, Henri-Georges Clouzot, in which stop-action and time-lapse photography are used to capture Picasso at work. Not many of the works he created for the documentary survive – but three hang in the Royal Academy exhibition, 'Picasso and Paper'. Here's how one of them came to be. Picasso and Paper is at the Royal Academy of Arts until 13 April 2020. (Credits: Royal Academy of Arts).