“Theatre people are very odd ducks,” Christine Baranski announces with a broad smile. “And Noël Coward knew that. This is an affectionate lens he is seeing them through.”

The New Yorker is talking about , Coward’s 1924 comedy of manners about the eccentric Bliss family, in which she will make her West End debut at the age of 74. Baranski plays Judith Bliss, a self-obsessed actress struggling to come to terms with retirement, opposite Richard E Grant as her writer husband, David, who is every bit as narcissistic as his wife.

The Bliss family – mum, dad, and siblings Simon and Sorel – squabble constantly, ignore their guests, serve terrible food, and generally behave appallingly. Yet, somehow, they are happy. “My wife and I divided the world into people who are in showbiz and those who are civilians,” says Grant. “Civilians are not as good at telling stories in the way that actors or writers tend to be able to, because they can dramatise or embellish things. That’s the dynamic of this family.”

Grant last appeared on stage in London some 20 years ago – like Baranski he is more famous for his career on screen. But both are thrilled to be back. “For me,” says Baranski, best known for and , “it’s perfect in the long arc of my career that this should be a bookend, because I trained at Juilliard, which I always felt was rather like an English actor’s training. And I worked in theatre for quite a long time and loved it, doing plays by Shakespeare and Molière and Chekhov. Then, in my 40s, my career took a turn into television.”

Both are relishing being in Coward’s world. Grant says: “[It’s a 102-year-old] play set in the time that it was written and in the clothes that it was written for. It’s not a high concept production set in an asylum on Mars. That’s very plausible… but we are both very grateful that this version isn’t trying to update it.”

They visited the Noël Coward archive together to look at the playwright’s papers. “What a world he lived in!” Baranski says now. “The letters from people such as Charlie Chaplin, Marlene Dietrich, Elizabeth Taylor and Richard Burton. It was another way of living. That’s what I want to communicate to people. It’s not heavy-handed, it’s not physical comedy. Think of champagne in a crystal glass. That’s what the audience should sip.”

Grant grins. Sitting side by side, behind a table, with Baranski elegant in cream Paul Smith and Grant in a bright turquoise shirt and pinstriped jacket, they look like a pair of recruiters interviewing me for a job. They have never worked together before, yet have clearly developed an easy rapport.

They certainly share things in common. Both, for example, had famously happy marriages but are now bereaved. Grant wrote a book called A Pocketful of Happiness about his late wife, the voice coach Joan Washington, who died in 2021 after “38 years of marriage, which in show business years is about 5,000”. Baranski met her beloved husband, Matthew Cowles, when he offered her a lift on his motorcycle when they were acting in Ibsen together. They were married 30 years before his death. “We were so blessed,” she says.

Both she and Grant are also enjoying life as grandparents. Grant shares his London home with his daughter, Olivia, and son-in-law, Florian, and his first grandchild is turning 12 weeks old when we meet. He’s loving helping out, but on grandparent terms. “It’s all honeymoon for me,” he says, with a smile. “I don’t have to stay up all night, and I am on the other side of the house, so I don’t hear anything. That’s the other great advantage of doing a play, because my life as a film actor is so peripatetic and being in London for the next three months and being at home during the day is a great thing.”

Three of Baranski’s four grandsons are old enough to come to see the play when they visit London. “I want them to come and see me on stage because it might be my last play,” she says, with a smile that indicates it might not be, really. Her own grandmother was an actress in the Polish theatre. “She was emotionally generous, fun and flamboyant and she informed so much of who I am. I think grandparents have an enormous effect on their grandchildren.”

The other thing they have in common, is that they are both in what Grant’s wife Joan affectionately termed the “condiment years”. Baranski hasn’t heard the phrase, and grins widely when Grant explains that it is about being “brought in for a bit of vinegar, mustard, spice”. “That’s brilliant,” she says.

Grant shot to fame in Withnail and I, but since then has specialised in great supporting roles including the sleazy chancer in Can You Ever Forgive Me?, which earned him an Oscar nomination. Baranski won an Emmy for supporting actor for in 1995, and after dazzling turns as a tough-talking lawyer in and its successor , she now holds court as the supremely snobbish Agnes van Rhijn in Julian Fellowes’s series .

“I won that Emmy with my first nomination. I think I’ve had 15 subsequent nominations which makes me one of the Emmy Awards’ biggest losers,” she says, with a laugh. Grant jumps in, eyes sparkling. “Oh yes, she and her great friend Meryl Streep sit and commiserate with each other. She’s won three Oscars but lost 21 others.” They both giggle, delighted.

In truth, Baranski considers herself blessed in her career – one highlight was working with Stephen Sondheim, who loved her concert performance as Mrs Lovett in Sweeney Todd. “It still brings tears to my eyes that I could make him happy.” And she adores her role in , which returns to screens in November. “Whenever I am moaning that my corset is too tight after 14 hours on set, I think ‘No bitching on the yacht!’”

“Just look how lucky we’ve been,” she continues. “Look at the length of our careers, consistently working, having marriages, children. And we still love it. Honestly, to be at this point in my life doing the kind of roles I am playing, I think my career is better than ever.”

Grant nods his agreement. “No bitching on the yacht! Exactly. I’m lucky at 69 still to be getting the jobs.” This autumn, Grant will appear in the second series of . “I am not allowed to say anything,” he says, cautiously. But he was thrilled to be asked. “I am obsessed with . I’ve watched every series, every iteration. I find it absolutely riveting.”

For now, though, he’s concentrating on . “It’s a wonderful part,” he says. “Because [David is] irascible, very impatient and volatile and clearly still adores his wife and finds his children almost intolerable. It’s a gift.” Baranski laughs: “At this point in our careers why would we do anything unless we can enjoy it? Judith Bliss is one of the great female roles; you get to play an actress who is restless, who feels she is ageing but still alive. So you actually get to do a lot of what’s inside you. It’s just fun.”