Helen George is in absolutely no doubt. “This is exactly the sort of show that we need right now,” she says. “Theatre really comes into its prime when the world feelsuncertain – and especially with a musical that’s as much fun and as lively and joyful as this one.”

The show in question is a new production of Cole Porter’s timeless High Society, opening at London’s Barbican theatre tomorrow. “It’s a wonderful, fabulous, sophisticated escape of an evening, with a huge orchestra and a big brass section,” continues the actress, 41. “The costumes are incredible, the songs are amazing and I’m over the moon with the cast and crew that I get to work with.”

High Society began as a 1956 American musical romantic comedy starring Bing Crosby, Frank Sinatra and Grace Kelly (in her final film performance before marrying Prince Rainier of Monaco). It was a musical remake of the 1940 screwball comedy film, The Philadelphia Story, based on the 1939 play of the same name by Philip Barry. Jazz artist C.K. Dexter Haven is hung up on his ex-wife and neighbour, socialite Tracy Samantha Lord. But she is engaged to another man. Matters are further complicated when a magazine reporter – in town to cover Tracy’s wedding – winds up falling for the beautiful bride. As she tries to decide on the ideal husband, each suitor works hard to convince her he’s the best choice.

“Tracy’s a very interesting character,” says Helen. “But why would we care about her because, on paper, she’s got it all. She lives in a fantastic house with so much wealth behind her. Ultimately, though, it’s a story about human relations.”

Helen may be best known to TV audiences as Trixie Aylward in Call the Midwife but she’s no singing ingenue. Two weeks after graduating from the Royal Academy of Music in 2004, she was part of the ensemble in Andrew Lloyd Webber’s Woman in White.

She has also worked as a backing singer for Elton John and sang (There’ll Be Bluebirds Over) The White Cliffs of Dover at Buckingham Palace on the 75th anniversary of VE Day in May 2020. She was on the cast album, too, of Lloyd Webber’s Cinderella.

But, Helen says, her role in The King and I, both on tour and in the West End a couple of years ago, eclipsed all of that by a country mile – “Anna [the lead female character] gets almost all the best tunes,” she says. Even so, it looks like Tracy is about to supplant Anna in Helen’s affections.

Equally, director Rachel Kavanaugh couldn’t be more enthusiastic about this project and believes the “glamorous, champagne-fuelled, chaotic, sexy, naughty and romantic” musical is a tonic for our serious times.

How familiar is she with the famous film? “Alarmingly so because it was part of my childhood,” she says. “I know it incredibly well.” So, it casts a shadow? “In a way. With a cast that included Crosby, Sinatra and Kelly as well as a cameo from Louis Armstrong, such an extraordinary cocktail of talent, how could it not?”

But the stage version, she insists, is adifferent beast. There are the famous songs from the film – Who Wants to be a Millionaire, Well Did You Evah! and the swooningly romantic True Love. But there’s a fair number of others, too, that have been shoe-horned in from the Cole Porter songbook. Among them are I Love Paris, Just One of Those Things, I’ve Got You Under My Skin and Let’s Do It. “The man wrote both the music and the lyrics,” says Rachel. “Genius is not too strong a word.”

Mike Connor, the rascally magazine reporter, is played by Freddie Fox in asurprise piece of casting. He boasts a host of theatrical roles as well as large and small-screen performances – perhaps most notably as Jeremy Bamber in the TV production of the murders at White House Farm – but this will be his first musical.

“I’d never seen the film,” he admits, “but it’s my sister Milly’s favourite movie. For a long time I’d been campaigning to do a musical. I got close twice but, many auditions later, I landed this one. And I’m particularly happy to be sharing the stage with Julian Ovenden, who is simply the best of the best. It makes you raise your game.”

As the new boy, Freddie, 37, didn’t want to let anyone down. “I’ve been having singing lessons for around 10 years now,” he says. “This is a moment I’ve dreamt of since I was a boy. It’s important to me to be as good as everyone else.

“As I sit here today, I’m more excited than terrified. This is a huge career milestone.”

And what about his famous family? Will they come and see his performance? He laughs. “Well, they’re not famous to me.”

For the rest of us, they’re pretty stellar: there are his parents Edward Fox and Joanna David, his sister Emilia, his uncle James and so it goes. “Oh, try and keep them away,” says Freddie.

Has this experience given him an appetite for more musicals? “If I can get through this run and the tour and feel technically on top of it at the end, yes, absolutely,” he replies. “I’m having the best time.”

Among his co-stars is Felicity Kendal, who plays Tracy’s mother. She had a high old time, she says, in Anything Goes at the Barbican in 2021. “So, when the same producer, Howard Panter, asked if I’d like to be in High Society, I couldn’t resist doing another Cole Porter at the Barbican.”

She’s now 79 (although looks 10 years younger) and likes to work. In the lastcouple of years she’s lost her husband Michael Rudman – father of her younger son Jacob – and playwright Tom Stoppard, with whom she enjoyed a lengthy affair.

Is there a sense in which work is a refuge in dealing with this double blow? “No,” she decides at length. “The word I’d use is an essential but then it’s been like that for all my life. Work is what I do; it’s part of my DNA. It’s always given me security and comfort. And I love being part of a company.” So, no question of retiring?” A throaty laugh ensues. “I don’t think retirement is a very healthy option unless you’re very, very active,” she says.

Could she ever have imagined at this stage in her career she’d have two musicals under her belt?

“A total surprise,” she replies. “We think we’re in charge of our own destiny. Ha! Well, just look at Freddie Fox. This is his first musical and he’s going to be the show’s surprise hit. You mark my words. He’s one to watch. But then so is Carly Mercedes Dyer. We were in Anything Goes together and that girl is going to be a major star.”

Carly was invited in by the producers to read the part of quick-witted photographer Liz Imbrie last autumn. It’s not hard to see why. As gangster’s moll Erma, she stole every scene in Anything Goes – her peerless singing matched by her comic chops.

She’s never seen the film version of High Society, though. “And I want to keep it like that until I feel I’ve really nailed the part,” she says. “I don’t want to do a replica of Celeste Holm’s performance. Also, being a black woman, I’ve got to work out how I’d fit into a society like this in the 1950s.”

She also pays back a compliment to Felicity. “I call her the Dame because she’s an absolute babe,” says Carly, 39. “She’s always got atwinkle in her eye. I keep saying to her: teach me everything you know.”

The only other cast member she’s worked with before is Nigel Lindsay, who was also in Anything Goes and plays wicked Uncle Willie in High Society. “In2009, he was in Matilda and I was in the chorus but I was a child then. Well, almost,” says Carly.

She’s really enjoying her partnership with Freddie, too. “We clicked the moment we met,” she says.

Rounding out the cast is Julian Ovenden, who plays Tracy’s ex-husband Dexter, the part Bing Crosby played on film. He says: “I love Philadelphia Story both as a play and a film but I’ve always thought High Society is slight and a bit flawed, although I do admire the score; I’ve sung some of the songs in various concerts down the years.”

But, as he points out, it was never conceived as a stage musical. “So, I was interested to see what was planned for this revival. This version feels like a good combination of a big Broadway experience but also a story that’s a little more sophisticated about complex, interesting characters.”

And what about that somewhat rakish moustache? “Let’s just say I’m workshopping it,” he says with a laugh. “It’s a period tache, redolent of the glamorous, Hollywood lifestyle of the Fifties.”

He couldn’t be enjoying himself more. “It’s a great combination of talent in the room, of energy in the piece and something that is unapologetically escapist. But beneath the surface bubbles, you discover the most important thing in life: true love, incidentally, one of the greatest songs ever written.”

• High Society runs now until July 11 at the London Barbican; for tickets visit HighSocietyMusical.com