Shirley MacLaine - The evening star

Over her 55-year career, Shirley MacLaine has gone from ingenue to grand dame, writing books and enduring mockery for her New Agebeliefs along the way. She tells Lesley O’Toole how she does it

Valentine's Day is Shirley MacLaine's 52nd film in her 75 years, but she is quick to sabotage previous self-generated hints at retirement. "I like playing other people since I was so many of them," laughs the woman as famous for her past lives (as paramour to founder of the Holy Roman Empire, Charlemagne, for starters) as her thespian ones. "I enjoy the whole pretence of playing like I'm someone else for a while. So I don't think I'll retire. They might retire me, but it won't be of my own volition. I'm at a place where I don't do anything I don't want to do and I reached that some time ago."

Valentine's Day is also MacLaine's first featuring her elfin ingenue self alongside her current more mature incarnation. Nothing to do with computer-generated imagery, it is – like MacLaine herself – a contradictory melange of old and new school. At an actual, terribly fashionable Los Angeles cemetery, where picnicking film-goers plonk down blankets beside gravesides for late-night screenings, a Valentine's Day lovers' tiff plays out between MacLaine's character (who has just confessed to adultery) and her screen husband of a half-century, Hector Elizondo. Running behind the bickering couple is the black-and-white oldie being screened, specifically a scene from MacLaine's 1958 film Hot Spell. In it, MacLaine is short-haired, stunning and, for most of its duration, kissing.

Today, too, in Beverly Hills, MacLaine is markedly monochromatic. She's wearing all black; a polo-neck under what she later tells me is a Chanel suit, with a pale blue Chakra Sky Spirit Steering necklace from her own collection (about £125 at shirleymaclaine.com). Her face is powdery pale, her lipstick almost purple. Only her trademark red-grey bob adds colour.

She smiles broadly when I ask how it felt to film the scene. "That was very interesting for me. Garry [Marshall, director] asked what picture would be a reflection of the love scene we're talking about between Hector and me, 50 years ago. I think I was about 18 or 19 in that scene we used. [She was actually 23 or 24.] I couldn't take my eyes off it, trying to determine, 'God how much have I changed!' "

She says she remembers every detail of filming Hot Spell that day. "It all went through my mind. The wardrobe, the prop master, the producer, the people who were and weren't good that day on the set. It's amazing how film makes you recall reality again in a whole different way. I thought it was brilliant that Garry would do that."

There's a sparkle in her face which belies her age (she has admitted to a face-lift at 50 but has done nothing since), but it is more than that. "I have zero stress in my life," she beams, looking appropriately serene and, deservedly, a little smug. She is after all a successful author perennially filed under New Age, or occasionally in travel sections, runs a website that amassed almost 20 million hits in its first few months, and lives mostly on a ranch in northern New Mexico where she says she often spots UFOs, never emails but voraciously devours newspapers online. She practices the Chinese meditative exercise Qi Gong every morning and goes nowhere without her dog Terry. They met in a past life too.

Understandably, MacLaine's startlingly eclectic film career is sometimes cited second. She has been nominated six times for an Oscar, first for 1959's Some Came Running in which she starred opposite Frank Sinatra and Dean Martin, then in 1960 for The Apartment, a sort of movie dream-team comprising herself, director Billy Wilder and Jack Lemmon as lead. She was nominated again for the dream team's next outing in Irma La Douce (1963), and in 1977 for The Turning Point before finally winning for what is for many her tour de force performance, Aurora Greenway in 1984's Terms of Endearment with Jack Nicholson. "I deserve this," she announced from the podium. "Of all my roles I would say that is still my favourite."

I am most surprised by MacLaine's seemingly insatiable appetite for self-mockery. She alludes to her own seniority in joking about the irony of filming in a cemetery replete with so many star corpses. "Yes, I spoke to them all evening. They were keeping me warm, keeping me cool. It was very very reassuring to me that nothing ever dies."

No one is joking about MacLaine's ongoing revival, which began in 2005 when she starred as quirky foil to some of Hollywood's current leading ladies (Bewitched with Nicole Kidman, In Her Shoes with Cameron Diaz, and Rumour Has It with Jennifer Aniston). "They're very much better actresses today than they were in my early days; less stilted, less formal, more honest, more willing to dig into the emotionality of it."

She has worked consistently since, a result, she says, of the universe's conspiring in her favour. "After 9/11 I kind of went into this place where I thought I am going to surrender completely to whatever the universe wants me to do. If you get out of your own way these things can occur and that's what I did. Just let it alone and it comes through. It's the most profound thing I've ever done. I've always been making things happen and now I don't."

MacLaine's career began under similar circumstances when the girl she was understudying in the Broadway play The Pajama Game broke her ankle. MacLaine went on, a legendary producer was in the house, and the next day she had a seven-year contract with Paramount Pictures. Her first film, 1955's The Trouble With Harry, was directed by Alfred Hitchcock.

Shirley (she was named for Shirley Temple) MacLean Beaty was born to Virginia native Ira and Canadian Kathlyn. She denotes herself an "overachiever" with some justification. At two she was taking piano lessons. At 12 she danced with the National Symphony Orchestra and by 18, was a chorus girl living in New York.

"Mum wanted to act and my dad used to tell me he wanted to run away and join a circus. I think he really meant it. So I've run away and joined my own circus because he never did. I feel my mum gave it all up to raise Warren [Beatty, her brother] and me. I think both us have basically done what our parents didn't do but wanted to."

Another change and quite seismic adjustment (perhaps also post-9/11) has been Beatty's shift in his views about his sister's second career. Formerly publicly sceptical of his sister's otherworldly leanings, he has come to admit she might have a point. He's not alone in that assertion, which thrills her no end. "They used to call me wacky with my spiritual stuff, 10 years ago. It's kind of mainstream now, and interesting that truth has become eccentric."

She wishes her much-younger co-stars the same enlightenment she apparently exudes. "But they never eat! They're always concerned with being so thin, I wonder how they survive." She has higher praise for Roberts. "There are people you've had a life experience with who you can tell the truth. And that's the most important thing in this town. The truth. We were friends on Steel Magnolias when she was just born. That's what I value so much about my relationship with Julia. She was contending with a director [Herbert Ross] who did not have a lot of sensibility. That's the truth, and I was very impressed with how she related to it. I also admire her today with what she's done in her life. Plus she was so good in Duplicity. She should be up for an Oscar for that."

MacLaine attributes her own longevity to "good genes, hiking, eating pretty well and my mom. She never really stepped up and said, 'Here I am', like most Canadians don't. So I learned from her, step up." Perhaps step back, too. At home in New Mexico, MacLaine prizes her solitude most. "I'm very much a loner. I read, write, am very attuned with nature. I could spend all day looking at the different colours of leaves. I don't think I could have done that when I was 30. It's an ageing process also but I've always been a loner."

Does she ever feel lonely? "Never. My idea of being lonely is to never be alone. That would be really seriously awful for me. I don't get bored doing much of anything. I was reading this guy's T-shirt the other day. It said: 'I Don't Think Much. So Therefore I May Not Be'." She has a good throaty laugh. "I think I'm getting to that."

She has two grandchildren whose mother is her only child, Sachi, the product of her union with Steve Parker, a marriage that lasted 28 years on paper, fewer in reality.

What would she like to pass on to them? "The personal courage to look at the universe within and don't let anybody laugh at you when you do it."

'Valentine's Day' opens on 12 February