Doe-eyed Kristen Stewart might just take the crown as Princess Diana

In a highly competitive field, the American actor has perfected the put-upon princess look for Spencer, the latest royal biopic

Some films have to work harder than others to get bums on seats. Some can charm audiences with big stars, or the lure of a continuing franchise, or the promise of a scene where King Kong takes a swing at Godzilla like he's half-cut in a Wetherspoons car park. And then, right at the other end of the scale, is Spencer.

Make no mistake, Spencer will have to be brilliant to make people go and see it. Better than brilliant, even. It will have to be the perfect movie; entertaining and fun and moving and so technically accomplished that film historians will come to view it as the moment that cinema entered a new epoch. Anything less than that and Spencer is done for.