The bow on her blouse “is a pointer to Thatcher, really,” says Roberts, who tried to accentuate developments in the women’s relationship through their outfits. The handbag is a recreation of those the Queen famously carries, by Launer, with similar recreations created for Thatcher. This Bruce Oldfield gown, in a shade of blue recalling Walt Disney’s 1950 Cinderella, represents the high point of a very successful tour. “It was a deliberate choice to put her in this,” says Roberts. “There is a lot of irritation going on, on that tour, but this dress was the moment you felt maybe they did love each other. There’s sort of romance and youthfulness. The dress is kind of crazy, pure 80s, shimmery, slightly trashy, but it just moves so beautifully at the dance, when it’s all breathless and exciting.” I often find that actors feel pretty fabulous when they put on a suit they would never wear in their personal lives. It always amuses me that Tobias, who plays Prince Philip, will stagger on set at some horrible early hour in an oatmeal sweater and trousers; an hour later he comes out in a suit and we all swoon.” Margaret Thatcher, played by Gillian Anderson verifyErrors }}{{ message }}{{ /verifyErrors }}{{ Prince Charles and Diana’s 1983 Australian tour took on existential significance for the royal family, coming at a time of burgeoning republican sentiment. Diana was strategically deployed in the charm offensive, photographed as a doting mother, with baby William on her hip, wearing a seemingly never-ending supply of photogenic outfits.

Apart from one iconic moment – the PM in knife-pleat skirt waving from the doorstep of No 10 – Roberts didn’t make facsimiles of historical looks but “absorbed all the images”. The pussybow blouse, an enduring symbol of female power, had come into fashion as women searched for an alternative to ties to wear in male-dominated workplaces – the US vice president-elect, Kamala Harris, even wore one for her historic acceptance speech this week. Thatcher’s blouses were created from silk, mainly found in Paris, though during the course of the series any softness disappears. “At the beginning she was quite grey – she looked ordinary – and as she gets more powerful she drops her voice and looks more streamlined with padded shoulders.”