Diane Paulus, only the third female director to win a Tony Award, is bringing the smash Broadway musical Waitress to the West End. She talks to The Stage about the differences between British and American audiences, how she loves audience interruptions, and why the hardest thing in the business is getting a new musical right.

On the first day of rehearsals, director Diane Paulus quickly realised she wasn’t in New York anymore. “There was a little jar of instant coffee and a giant bag of 450 tea bags, and I knew I was in London.

“I’ve been delighted with the British cast’s enthusiasm for this musical. They’re so committed to the depth of the show, which has been so rewarding and encouraging to me.”

A native New Yorker, Diane is a hugely respected theatre and opera director in the US and is the artistic director of the American Repertory Theatre at Harvard University. In 2013, she became only the third woman to win a best director Tony, for her revival of Pippin, and a year later was named on the Time 100 list of influential people. She has worked on a string of musical theatre productions that have proved hits with audiences and critics.

“The reason I do musicals is not just because they’re entertaining, but because they reach a broad audience through music and pop culture. They tackle important subject matters at the same time, and they’re emotional. The depth of Waitress is really why I’m in it and committed to the show. There’s usually a leading-man slot, but in this musical all the men are supporting the female protagonist and the other female leads.

“When we put the team together, it wasn’t a casting agenda to put only women in the four creative roles. It was really about finding the best person for the job – starting with the best composer out there, who maybe isn’t from the musical theatre world but from the pop one, who could catch the tone of this quirky, indie film. Sara is at the top of her game both as a composer and a lyricist. It was also that way for the book writing, for choreography, and for musical direction. It just so happens that we have women at the top of their game in all these areas.”

She told the singer to watch the film “and to go inside her heart and soul and write the first song that came to her. I told her not to worry about the plot, or think about a treatment or outline of how it would be adapted. I told her to simply respond to the film.”

Diane was interested in working with Sara, after producer Barry Weissler gave her a list of films to watch that had the potential to become musicals. She selected Waitress and had an “intuition” that Sara might be right for it, despite her never having written a musical theatre score. She arranged a meeting to find out if she had an interest in theatre, “and lo and behold, she did”. A couple of weeks later, an MP3 file arrived in Diane’s inbox. It was ‘She Used to Be Mine’.

“I listened to it, with that feeling: ‘Here we go, cross my fingers.’ And when I heard it, I knew we had a show. It was clear from that one song she understood the character of Jenna so deeply, and that her lyrical ability was sophisticated and deeply moving. And it’s still the signature song of the show, it’s the show-stopper. And now it gets sung by everybody from 12-year-old boys to a cappella groups. It’s a phenomenon. Sometimes as a pop writer, you’re pressurised by your label: ‘This is who you are, this is what you should sound like.’ By writing a musical, she was liberated to write different songs, different styles and points of view. She relished that opportunity.”

Diane suggested starting the process at the ART – just across the Charles river from Boston – where she has been artistic director since 2008. “It was a safe place that would give her room to try it out. For someone who was composing for the theatre for the first time, you need that space.”

“In my experience on Broadway, and it has now happened in London in the same way during previews, people are tapping me on the shoulder and thanking me for doing this show because it changed their lives. And there are more men than women telling me that it helped them get out of a dark place or an abusive relationship.

“That isn’t to say there aren’t a lot of women seeing the show. It’s affirming to me that we have a female protagonist, but actually it’s a human story about what happens to us when we’re made to feel less than we are, and how we have to fight to gain our sense of self – and the resilience we find from unusual places.”

Diane is currently steering another new musical, Jagged Little Pill – based on Alanis Morissette’s 1995 album – to Broadway. It opens this autumn after she directed it at the ART last year.

“Doing a new musical is never easy. It’s not brain surgery, but sometimes it feels close to it. In the business it is known as the hardest thing to get a new musical right. There are so many rules and yet in a way you have to break all the rules. There are things you rest on in making good musical theatre. Obviously there’s: what’s the journey of the show? Who are you following? How are you rooting for them? And where are the songs landing and why are they singing? But I believe the best musicals take off because of something else. Some magical thing that happens, when all the ingredients – to use a baking metaphor – hit correctly. There’s an alchemical thing that happens, when the vision for the show matches the music, the choreography and the story, and then it ignites an audience.

“And that’s why I love the theatre. It’s all about whether it connects. We are not a form that exists where you can click ‘go’ on your laptop and watch it alone in your living room… the art, especially of the musical, is the energy and transmission to an audience. You can argue in a play that the audience is more invisible, that there’s a fourth wall and you’re just a voyeur watching drama happen. In a musical, you’re applauding every number. It’s like an opera, you’re stopping the action to say you love that, you recognise that. I love those interruptions. For me, the whole point of the theatre is the partnership with the audience.”

When ‘She Used to Be Mine’ stopped the action for 35 seconds during a preview in London, the resident director turned to Paulus and asked what was to be done – was this just allowed to happen?

“I replied: ‘Yes, it’s actually an affirmation of the story.’ The audience is saying to the character: ‘I see you, I recognise you, I am rooting for you.’”

“When you do a revival, you’re mainly focused on how you are interpreting the story and what is the production you are envisioning. With a new musical, you have all those pressures – what’s your set design, what’s your choreography, how does the show look, what are your production ideas? – and simultaneously, especially when you’re premiering it, is the story correct? Do we have the right song order? Is the structure working?

“There are things you can only see once you have it in front of an audience. And when you do it again, you find new things every time. I just scheduled a rehearsal on Broadway for next week, as I want to input one of the changes we’ve done for London. I asked my Broadway stage manager if three years in I was allowed to change it again, because I think we’ve made it better.

“The work in the rehearsal hall on both Broadway and the West End is universal. It’s always about work between the director and the actor to gain a sense of trust and unlock the actor into their most creative zone. That doesn’t really change.”

The biggest difference is systemic, not artistic – how the show is organised. “In the West End you have a resident director who I’m currently training, a stage manager who is in charge of the production technically, and a company manager who is doing the schedule. We don’t do any of it like that in the US. We don’t traditionally work with resident directors. On Broadway, the production stage manager handles everything: the schedule, the rehearsals, the tech and the maintenance of the show.”

The audiences are also different. She fondly recalls the first time she worked in London in 2000, when her immersive disco production The Donkey Show transferred from the Edinburgh Fringe to a venue called the Hanover Grand near Oxford Circus. “Every time I walk by it – the venue itself is no longer there – I get very nostalgic. I was a young director and I made that show with my now husband Randy Weiner. It was a dream come true when we came to London. And one of the things I was struck by is how different the audience was here.

“Maybe I’m being naive, but the way I feel about the British audience – which is also an international one in London – is that they are listening to the story in a way that I don’t always feel they do in America. I called Randy after the first preview of Waitress, and said it was just like we experienced with The Donkey Show: people would watch the story points of it with such intensity in a way that they didn’t so much in America.”

“The audience is happy to be there. It’s a social thing, every theatre in London has all these little rooms where people have drinks, they come in groups and on dates and are happy to be at the theatre. Broadway is doing great, but sometimes I feel the culture inside a Broadway theatre is to get you in and get you out. If the show is short that’s good, you aren’t there to drink and enjoy it.”

And on the ART, she said: “Not only do I have an incredible staff and team, but we have a great audience in Boston who have come to love the ART as a home for boundary-breaking musicals and theatre. The opportunity to give Sara Bareilles her first shot at a musical is why we’re there – to take risks. Now it’s easy to look at Waitress and say, that wasn’t a risk: it’s a Broadway hit. But when you start, you don’t know what you have, you don’t know if it’s going to work and you need a place where you have the room to take a risk. That’s the role of our theatre.”