Back to the Future saw Michael J Fox’s Marty McFly time travelled back 30 years to 1955. After meddling with the past, the teenager returned to a new version of 1985 he created where his parents were happy, healthy and wealthy. No longer was Biff Tannen bullying his father, but instead George McFly had become a successful sci-fi writer while his old nemesis was outside washing his car.

But now a popular fan theory argues that Marty McFly’s actions in 1955 actually improved Biff’s life.

Upvoted over 5,000 times, Reddit user SatNav wrote: “As a youngster, I watched Back to the Future, and was pleased to see at the end of the film that Biff had got his ‘just deserts’.

“‘Hah!’, I thought, ‘Biff is a nobody now, he has to…