“Here’s a typical exchange: at the time of our interview, the US election is still three weeks away, so we talk about that. ‘Every worst instinct in mankind has been played on [by Trump], and for me that’s just anathema. Biff is president!’ he says, with justified exasperation, given that Back To The Future’s evil bully Biff Tannen was modelled on Trump. I ask how he felt during the 2016 campaign when Trump mocked the New York Times reporter Serge Kovaleski, who has a disability. ‘When you see your particular group mocked, it’s such a gut punch. It’s so senseless and cheap. There’s no way I get up in the morning and mock orange people.'” Michael J Fox: ‘Every step now is a frigging math problem, so I take it slow.’