When Helen Mirren is relaxed, her face must look a bit, shall we say, grumpy. While she’s lost in thought, strangers will approach and tell her to cheer up. ”I hate that!” says the actress, sipping coffee at Claridge’s Hotel in London. ”Someone comes up and says, ‘Cheer up, love!’ You know, f— off! I want to head-butt them!” Mirren hardly seems the head-butting type. Clad in a cleavage-revealing, pale pink dress, the British stage and screen vet looks considerably younger — and sexier — than her 61 years would suggest. Though a real-life Dame (an honor bestowed on her in 2003) and practically royalty among actors, Mirren isn’t afraid to say what she thinks. In August, when she accepted the Emmy for playing the title role in HBO’s miniseries Elizabeth I, Mirren claimed that her greatest triumph was not falling ”ass over tit” on her way to collect the trophy.

Thanks to her latest role, we just might have more of those speeches to look forward to. In The Queen (opening this week in New York and L.A.), Mirren plays England’s current monarch, Elizabeth II, during the days between the 1997 car crash that killed Princess Diana and her funeral. The movie focuses on newly elected prime minister Tony Blair’s attempts to persuade the Queen to join in the unprecedented national mourning that the death of ”the People’s Princess” has provoked. Alternately damning and sympathetic toward Queen Elizabeth, director Stephen Frears’ (High Fidelity) film is complex and controversial. Though the British press hasn’t shied away from dredging up Mirren’s youthful support for the antimonarchist Workers’ Revolutionary Party, her performance has inspired critics to rise above politics: Even the royalty-supporting U.K. newspaper Daily Mail declared that she should ”win at least a nomination for Best Actress at next year’s Oscars.” (She has been nominated twice, as supporting actress, for 1994’s Madness of King George and 2001’s Gosford Park.) Oscar nod or no, Mirren shouldn’t expect any invitations for tea at Buckingham Palace. ”I was full of trepidation,” she says of considering whether to sign on for the project. ”You know that the media is going to be on this like flies on s—. Every word out of your mouth is going to be scrutinized.” Still, once Mirren committed, there was no hesitation. ”She just sort of gets on with it,” says Frears. ”Most of the time my job was to stay out of the way and keep my mouth shut.”

Which is not to say there weren’t tough moments. ”I saw the costumes and literally burst into tears,” Mirren says of Her Highness’ more-horse-lover-than-clotheshorse taste in head scarves, sensible skirts, and galoshes. ”But after the initial shock and the realization that I had to let go of vanity — that I had to pull my head back and deliberately give myself a double chin and wrinkles — once I got over that hump, I loved it.” The role is hardly Mirren’s first — or even second — royal figure. ”Shakespeare didn’t write kitchen-sink dramas,” defends the actress. ”Certainly, the maturer roles in Shakespeare are all queens. So, I’ve played a few. But I’ve played working-class women as well!” Indeed, Mirren achieved international stardom as dogged but troubled detective Jane Tennison on the TV series Prime Suspect. In November, PBS will air the seventh, and final, installment. Of her decision to end the saga, she simply says, ”Because it’s time.”

Even early on in her career, Mirren took risks. In her 20s, the actress’ sensual stage appearances with the Royal Shakespeare Company earned her the sobriquet ”the sex queen of Stratford.” The queen then expanded her territory with 1979’s Caligula, the notorious Penthouse-backed soft-porn fest with Malcolm McDowell and Peter O’Toole. Those actors subsequently denounced the film, but Mirren remains refreshingly fond of it. ”I saw a bit of Caligula recently,” she says. ”And, within the craziness, there’s a really interesting, savage film.” The daughter of leftist parents, Mirren grew up in London. She now lives in London and L.A. with her husband, director Taylor Hackford (Ray), 61, whom she met on the set of 1985’s White Nights. Wherever she’s living, Mirren leaves her character on set. ”I never take stuff home with me, it’s not my style,” she says. ”My husband would have a fit if I came back as the Queen.”

Mirren’s sole encounter with Her Majesty was at a polo match a few years ago (she was invested as a Dame by Prince Charles). ”People always say [they] met the Queen and she was so charming, so sweet, so twinkly. And you go, ‘You arse-licking groveler!”’ she declares, with a laugh more dockworker than Dame. ”But, goddamn it, she is!”