Meet the cast of King Charles III

Unlike the other main actors in King Charles III who had performed the play for more than two years on stage, 35-year-old Charlotte Riley was a new recruit, her freshness intensified by never having seen the theatre production either. So, for her, filming was like jumping aboard a moving train.

“It was quite daunting,” Riley concedes. “But a friend of mine cleverly pointed out that coming in late to a situation where everyone knew what to say and do better than you was what it was like for Catherine when she joined the Royal Family.”

The actress and the duchess are almost precisely the same age — born ten days either side of New Year 1982, both are mums at similar ages — but, as Riley’s warm Tyneside accent makes clear there are differences vocally. As an “anchor” word, to get into the accent, Riley used “William”, which the duchess delivers in a rather stern way, with, the actress notes, “extended L sounds.”

Riley learned this from the Duchess of Cambridge’s few formal interviews, but also the clips on YouTube in which people had filmed encounters with the duchess on their phones: “She’s still on public display, but slightly more intimate and unguarded, so that was revealing.”

Charlotte Riley in King Charles III

Film footage wouldn’t help, though, with the dark side of the character, as in the play’s mock-Shakespearean scheme when Catherine is like Lady Macbeth, goading her spouse to seize the throne. “She is,” agrees Riley. “But I prefer to see her actions as pragmatic, her business-brain understanding that the Royal Family has to remain relevant to the public. Some people might see it as ruthless, but it can be seen as sensible.”

Riley has her own experience of paparazzi attention (she’s married to Tom Hardy, with whom she met and starred with in Wuthering Heights in 2009), but had to imagine another aspect of Catherine’s public life. Seeing herself as “not someone who’s fashion-minded”, Riley was fascinated by playing a woman who, by wearing the same dress twice, or a hemline higher or lower than expected, can make headlines: “It would drive me nuts having a team of people just working on how you look. I’m a young mum, so I can’t always be worrying about my Sunday-best.”

Aside from Wuthering Heights, Riley is also known for appearances in The Take, The Town, DCI Banks, Close to the Enemy and Jonathan Strange & Mr Norrell, with recent movie roles including Edge of Tomorrow, In the Heart of the Sea and London Has Fallen. She also features in BBC2's Peaky Blinders, first appearing in series two along with partner Hardy.