‘What do you think the English will say?’ Pablo Larrain on his pop horror Diana film

It all looks ever so Sandringham. Formal evening garb, dining table the length of a cricket pitch, royalty nibbling in silence. As a tableau vivant it might be lit by Lichfield and styled by Hartnell. And yet something is awry. The beautiful princess feels stifled. She grabs at the tourniquet of pearls roped round her neck, whereupon it snaps. Huge gems plop into her gloopy green soup. Dauntlessly she dips a spoon in, feeds a pearl into her mouth and takes a pulverising bite. This royal Christmas is not normal for Norfolk.

Spencer is the latest entertainment seeking to decrypt the myth of Diana, Princess of Wales. Its opening credits position it as ‘a fable from a true tragedy’, and the result is a pop horror genre flick — more Angela Carter than Barbara Cartland — whose critique of the Windsors makes Peter Morgan and Stephen Daldry look like cowering royalist lickspittles. When she arrives at Sandringham for three days and nights of psychological torture, Diana is forcibly weighed in the atrium, then issued with a strict rota of outfits to wear. Her maid and confidante, a sort of nice Mrs Danvers, is banished. Her curtains are stitched shut. The midnight flits, walk-in fridge raids and bulimic emissions are reported back to a poker-faced equerry on secondment from the Stasi. No wonder she starts seeing the ghost of Anne Boleyn.

The architect of this phantasmagoric vision is Pablo Larrain, who commissioned the script from Steven Peaky Blinders Knight. The Chilean director, thickly bearded and softly spoken, had never filmed in the UK before (and still hasn’t: Spencer, perhaps amusingly, was mainly shot in German castles). ‘I’m a republican,’ he declares, ‘and I would probably be in a big deal of discomfort if I were living in a country that has a royal family.