Control director Anton Corbijn’s first documentary, Squaring the Circle (The Story of Hipgnosis), is a fascinating and suitably maverick snapshot of a richly creative moment in music history, told through a couple of disreputable hippies who designed some of the most iconic album covers of all time. The team behind the cover art for acts such as Pink Floyd, Led Zeppelin, 10cc and Paul McCartney, Storm Thorgerson and Aubrey “Po” Powell, AKA Hipgnosis (the name came from a piece of graffiti by Syd Barrett), operated in a happy Venn diagram intersection in which vast record company budgets overlapped with an equally generous supply of hallucinogenic drugs. The rest is rock history.