They begin to cheer as soon as Angela Lansbury emerges, early in Act 1, with a curly, red wig and accent thicker than an overdone Sunday roast. Each night, the applause serves as a reminder that this moment is special.

“It’s a feeling of real pride to be up there with her and feel the extraordinary warmth that comes across from the audience,” says Charles Edwards, formerly of “Downton Abbey” and now playing writer Charles Condomine in the touring revival of Noël Coward’s supernatural comedy, “Blithe Spirit.”

Statistical realities may suggest that it is simply unheard of for an 89-year-old woman to be at the top of her game in a live, theatrical production, but Lansbury isn’t interested in proving a point by simply stepping onstage. Each night, she plays the quirky and eccentric medium Madame Arcati with the energy of a desperate understudy. She dances, flops over a chair and slams home Coward’s zingers with the precision of an atomic clock, the panache of a seasoned comic.

And “Blithe Spirit,” which arrives Tuesday at the National Theatre, is nothing short of a smash, a play touring to packed houses in an era when plays rarely tour, especially not English plays written during World War II. Though Lansbury isn’t onstage as long as Edwards and the other “Blithe” leads, Charlotte Parry and Melissa Woodbridge, everyone involved acknowledges that she’s the reason for that success. Her face is on the advertising flags installed on streetlights in Toronto and on the posters outside the Princess of Wales Theatre. Lansbury is the first to bring up her 12 years as the sleuthing scribe Jessica Fletcher on television’s “Murder, She Wrote.”

“I know that I’m the hook to get the people in the theater,” says Lansbury. “In most instances, 80 percent of the audiences are coming to see Jessica Fletcher. The fact that I’m going to give them Madame Arcati is a surprise, but they love it. Thank goodness.”

Angela Lansbury as Madame Arcati and Susan Louise O’Connor as Edith in the 2009 Broadway revival of Noël Coward’s “Blithe Spirit.” (Robert J. Saferstein/Robert J. Saferstein)

The role is, Lansbury says, one of her favorites, no small thing for a woman who has taken on more than a hundred, starting with her Oscar-nominated film debut in 1944’s “Gaslight,” continuing on to Broadway and five Tony Awards, and then her most popular spin, as Fletcher in the TV series that ran from 1984 to 1996. How long has she been performing? Of the 50,000 registered members of the Actors’ Equity union, Lansbury is the second oldest.

“I adore to play really great, well-written comedy,” Lansbury says during an interview in Toronto, where “Blithe Spirit” has been playing before wrapping its four-city tour in Washington. “And Arcati is terribly funny but absolutely the most earnest, well-meaning woman you could possibly imagine. You can’t help but laugh at her and laugh with her. Nothing she does is for the sake of the joke. This is the woman and the character.”

Lansbury, on this day, is wearing a pink blouse, pearls and gold flats. She’s full of energy, good humor and strong opinions. She’s not afraid to share her relief that executives abandoned an attempted reboot of “Murder” set to star “The Help” actress Octavia Spencer. But she is cagey when asked to compare the people she plays onstage with her real self. Lansbury also does not call herself a star, describing herself as the ultimate character actress. She takes great pride in her range.

“I’ll put on a false ass, false anything, to change myself to become somebody else,” Lansbury says. “I’m never going to be me.”

The me side of Lansbury’s life has been well-documented. Born in London. An Oscar nomination while still in her teens. Then, more than a decade of secondary roles in a Hollywood system that didn’t properly cast her.

Lansbury’s film breakthrough came as the villainous mum in the 1962 political thriller, “The Manchurian Candidate,” earning her a third Academy Award nomination. (She would finally receive an honorary Oscar in 2013.) Her career then took off onstage, as Lansbury scored a Tony in the title role of 1966’s Broadway premiere of “Mame.” A series of stage and screen roles followed until she landed in the fictional Cabot Cove, the coastal Maine setting for “Murder, She Wrote.” Though Lansbury says that film and television roles no longer come her way, she’s continued to thrive in the theater.

It was back in 2009 that Lansbury won her fifth Tony for a revival of “Blithe Spirit” on Broadway. The current production, which premiered in London’s West End in 2014, is also directed by Michael Blakemore but has been reshaped. The set is different, as is most of the cast. Lansbury declines to explain why she feels this version is better. She doesn’t want to say anything that reflects poorly on the previous production. Blakemore is only slightly more open, describing this “Blithe Spirit” as more British.

“It was successful on Broadway and had a decent run and made money but I never felt it was quite right,” he said. “We have an English cast in this version, and the English bring to a Noël Coward play what an American cast would bring to ‘Death of a Salesman.’ One can’t imagine ‘Downton Abbey’ being played as persuasively by an American cast.”

One thing Blakemore says hasn’t changed is Lansbury.

“It’s beautiful acting,” Blakemore says. “She is the definitive Madame Arcati.”

But what about her age? Blakemore, himself 86, says that he hasn’t made any allowances. And Edwards has seen no sign of Lansbury slowing down.

“In L.A., they had us doing these five-show weekends,” Edwards says. “Which we were all bowled over by. But you bite your tongue if you say how tired you are, because Angela simply doesn’t do it.”

If Lansbury does make one concession to age, it is to wear an ear piece.

“I have a man on the end of the line,” she says, motioning to her left ear. “Tom here and Tim in London. If I suddenly lose it — this happens with all actors at one time in their lives, and certainly in my age bracket, it happens — he will throw me the word which will allow me to continue almost unbroken. It’s often just a word.”

Otherwise, she thinks nothing of age.

When told that she is the second-oldest registered member in Actors’ Equity, she asks who is older. Chicago actor Mike Nussbaum, 91.

“Tell him to watch out,” she smiles. “I’m coming on behind him.”

This is, she concedes, her last tour. Los Angeles, the first stop on the road, was a treat, a chance to perform live for the first time for family and friends in her adopted home town. But the schedule can be grueling. In Toronto, frigid temperatures have left her “trapped” in her hotel room.

And she has nothing left to prove. “Blithe Spirit” is just the latest reminder that Lansbury remains that rare combination of critically acclaimed and marketable. She just learned that she has been nominated for an Olivier Award for her London run. It would be her first.

In Toronto, crowds have been streaming into the Princess of Wales Theatre.

They applaud Lansbury’s entrance, roar with laughter as she performs the jagged, loping dance meant to summon the spirits during a seance. They cheer the cast, particularly Edwards, but stand only when Lansbury appears for her curtain call.

“She doesn’t look like she’s 89,” says Paige Morgan, a 37-year-old English instructor and doctoral student who remembers religiously watching “Murder, She Wrote” as a girl. “I wasn’t sure she was going to pull off Madame Arcati’s dance, but she killed it.”

Blithe Spirit March 17-29, National Theatre, 1321 Pennsylvania Ave. NW.

202-628-6161. $48-$203.