Stopping Trump, reforming Facebook and risking his life to make a Borat sequel. In an exclusive interview, the actor unveils his plans for a revolution – and reveals how it feels to come out as himself

Seven months ago, Sacha Baron Cohen was in the back of a speeding ambulance. It was an escape car, and he was fleeing a gun rally. The Borat producers had chosen the ambulance as it could blend in, accommodate a small film crew and, if necessary, hasten a trip to hospital.

Baron Cohen – dressed as Borat, himself disguised as a country singer – had just led the crowd of far-right conspiracy theorists in a singalong. At first, they happily joined in: “Obama, what we gonna do? / Inject him with the Wuhan flu.” Then one or two smelled a rat. Then they all stormed the stage.