How to make a Hollywood star sound like Princess Diana

Kristen Stewart, the star of Spencer, is interviewed at the premiere of the film at the Directors Guild of America in Los Angeles. Photo / AP

Tim Robey talks to voice coach William Conacher, who helped Californian Kristen Stewart find her inner Spencer.

How do you set about transforming Kristen Stewart, the gruff-voiced, frequently mumbly, famously introverted Californian star best known to the world as Bella Swan from Twilight, into Diana, Princess of Wales? The makers of Spencer have all the answers, in terms of costuming, comportment, hair and makeup, and Stewart has bucketloads of acting talent to tie all that together.

But they also have the voice to worry about — and it's here that dialect coach William Conacher comes in. It was Conacher who helped Emma Corrin perfect Diana's voice for The Crown. That was perhaps an easier task given Corrin's background — born in Royal Tunbridge Wells, boarding school-educated. It was Conacher, too, who coached Naomi Watts for the ill-fated 2013 Diana film. Watts, who was born in England but raised in Wales and Australia, must have been a sterner test.

"I have a lot of Diana in my history," Conacher says, even if his list of credits over the past 15 years extends far beyond her, to the likes of Cillian Murphy's period Brummie in Peaky Blinders, or Rami Malek's Oscar-winning Freddie Mercury in Bohemian Rhapsody, as well as his villain, Lyutsifer Safin, in No Time to Die.

When we talk he's en route to Elstree Studios, for work on series five of The Crown, where he's assisting Imelda Staunton, who's taking over as the Queen, and Elizabeth Debicki, who's replacing Corrin in the role of her most famous daughter-in-law.

Princess Diana's voice is posh, but not royal posh. Photo / Supplied

Conacher works exclusively with actors: he trained as one for three years. After stints in advertising, he re-entered the thespian world and taught at Rada for eight years, where he worked with such soon-to-be-famous names as Ben Whishaw, Tom Hiddleston and Andrea Riseborough.

Spencer fell into Conacher's lap through a long-standing connection with its screenwriter, Steven Knight (who also created Peaky Blinders), but the process of getting hired was, as he puts it, a comedy of errors.

"There was a mix-up with my agents," he explains. They told him that the Argentinian Pablo Trapero was directing it. (In fact, Spencer is the baby of Chilean auteur Pablo Larrain.) "I didn't know Trapero's work, so I got hold of this movie of his, The Clan, watched it, loved it and then the call was set up with Pablo the next day."

The wrong Pablo, unfortunately — who politely had to correct him when he started rhapsodising about The Clan. "Luckily, I had seen [Larrain's previous biopics] Jackie and Neruda. And he couldn't have been nicer about it."

The next thing he knew, Stewart was phoning him and their work began. "We started about three and a half months before the shoot. And it was quite an interesting process, because we didn't touch the dialogue for a long time."

Conacher's method when he's analysing a person's voice is to start off with video footage. "First I watch it without listening. I turn the volume down so I'm looking at physically what they're doing. Then I try to start speaking in what I imagine that voice would be like. And then I'll do the opposite — I'll cull the audio and just listen to it on MP3, listen again and see how it makes me move. And then I think, okay, what physical changes do I have to make to sound like that.

Kristen Stewart as Princess Diana in the movie Spencer. Photo / Shoebox Films

"Our politicians, for instance, have quite polarising voices. Sometimes it's literally about the placement of the larynx. So Gordon Brown, for example, has that kind of pushed down larynx voice, whereas Harold Wilson's is vairy haigh. You're looking for the thing that will distil it for the actor — not the cheat, exactly, but the most obvious way in."

To guide Stewart over those months of rehearsal, Conacher supplied her with what he calls a "drill sheet", with phrases to help her master specific vowels. Here's a sample: "The farmer transported the plants from France in a cart across the grass. Then he had a bath." Imagining the different ways that might be pronounced by an American born in Los Angeles, then a Brit, then a posh Brit, and then specifically Princess Diana gives you some idea of the sculpting process involved.

"We did that for really quite a long time, and we also worked on transcripts of speeches.

"By the time we started working on dialogue in December, she'd cracked all the things she had found difficult."

Stewart, he says, had learnt a British accent for Snow White and the Huntsman (2012). "I have to say she had a pretty solid grasp of RP before we started — it was just the Diana of it all we got specific about."

Kristen Stewart, the star of Spencer, is interviewed at the premiere of the film at the Directors Guild of America in Los Angeles. Photo / AP

What are the tricky aspects of Diana's voice, then? "She's posh, but not royal posh. So it's getting that balance. Like, her o vowel is really specific, because it's not 'eyew', like the Queen, it's more like, 'doughn't'."

"There's a great physicality to playing her, too. She does a lot of quirky things with her jaw and her head. And she was performative, as a person. I think we ramped that up for the film."

Though Conacher is generally credited as "dialect coach", there are many things to do with jaw, neck and face movement that fall into his purview.

Conacher's is a behind-the-scenes role that puts him in the firing line. He points to the Times review of Spencer, which specifically lambasts his work as having "produced nothing but a strange, strangulated whisper". "To be honest," he tells me, "strangulated whisper is kind of what we were going for!"

Conacher is happy to praise the work of others. He was bowled over by the ensemble work in HBO's TV drama Mare of Easttown, set in a Philadelphia suburb. "I absolutely believed that they were all from the same place."

But with Spencer complete, and Debicki's performance yet to be unveiled, Conacher sounds ready to leave the people's princess behind. "After Elizabeth, I'm pretty sure I'm not going to do any more," he says. "That might be the end of the road for me and Diana."