ALL women over 50 have reason to be grateful to Helen Mirren. Of course, those lists of ''world's sexiest women'' and the like are foul in themselves, but the fact they regularly include a 67-year-old actor - especially one who so often embraces roles involving dowdy costumes and a full set of wrinkles - does shift the goalposts. ''She's got a matriarchal authority, but she's very, very sexy,'' said bad-boy comedian Russell Brand, who asked for Mirren to play his butler in the (woeful, actually) remake of Arthur. ''I would happily lay for hours, my head upon her legs, and look at her.''
The really gratifying thing, however, is that Mirren's sustained magnetism has less to do with the ''big tits, blonde hair, Diana Dors, blousy kind of thing'' - her words - she has battled since her youth as it does with her seriousness and self-possession. In fact, that was always the essence of it. When she was 30, she did her first chat show with Michael Parkinson, an interview that is now a YouTube favourite and a fine capsule illustration of why feminism happened.
''You are, in quotes, a 'serious actress','' he leered at her. ''Do you find what might best be described as your equipment hinders you in that pursuit?'' Mirren was then the leading lady at the Royal Shakespeare Company. She remembers being thoroughly intimidated, but nobody would have guessed it. ''How dare you,'' she said quietly. ''Describe in detail what you mean by 'my equipment'.'' That was it, right there: the flare of Mirren's allure.
All these decades later, we are here to discuss her role in Hitchcock, playing opposite Anthony Hopkins as the director's wife, Alma Reville, a screenwriter and editor. Alfred and Alma met in the 1920s, right at the beginning of Hitchcock's career; they were together until he died in 1980. The film is based in part on their daughter Patricia's biography of her mother, who was apparently the only person who could influence him.
It might not have been a marriage that lived up to expectations in our Viagra age: the bedroom scenes in Hitchcock would have satisfied the meanest censor in the Hays Office, with husband and wife tucked chastely into separated singles. What we do see, however, is Alma vetting the script of Psycho, suggesting actors, insisting there should be music during the shower scene; being one half of a team.
Most of these efforts went uncredited: another casebook example, albeit more diffused, of why feminism was needed.
But then, Mirren mused in an interview with The Washington Post, what would the credit have been? ''You know: adviser? Wife-adviser?'' Movie history is full of unsung heroes, she says now. ''Probably most of them women. But, you know, film is the ultimate collaborative medium. I've been on films where the first assistant director is the one responsible for the film being as good as it is. Or the cinematographer.''
Marriage too, she points out, is also primarily a collaborative partnership. Mirren is married to Taylor Hackford, director of An Officer and a Gentleman and Ray, whom she met when he directed her in White Nights (1985). ''Yeah, sex is great and lust is wonderful, but it really isn't the only thing that holds people together in relationships. Far from it - far, far, far from it. Often it's the thing that drives people apart. My marriage is very successful. Whether we have sex or not is none of your business, but what holds us together is our partnership.
''The nature of the way Taylor and I operate, unlike Alma and Hitchcock, is that we let each other do our thing. He lets me do my thing. I understand, as a filmmaker's wife, the amount of obsession you need just to get the film made, the tenacity you need, the complete absorption of the job. You can't be the kind of wife who says, 'Oh, I made dinner and you didn't come home for it!' You can't be that wife. You have to be supportive. We don't criticise each other. Maybe 10 years later, I can say, 'It was a bit slow; maybe it would have been better five minutes shorter.' But at the time, you don't need that because there are enough people out there sticking the knife in.''
Mirren was never a Hitchcock fan herself. She met him once when he was seeing young actresses for Frenzy, his second-last and nastiest suspense film. ''I didn't really like him, and I know he didn't like me very much. He certainly didn't cast me. He took one look at me and went, 'Oh, good god. She's going to be a nightmare,''' she says. As far as she was concerned, Hitchcock was old hat. ''I was ignorant and stupid and I didn't understand he was the great filmmaker that he was, but I think a lot of the film industry didn't understand that then.''
She was no more enamoured at the time of the New Hollywood of the '70s, now revered as a golden age. ''You know, I didn't like Five Easy Pieces. I thought it sucked, more because I didn't like the female characters. I can just remember going, 'Well, there's nothing here for me.''' Her own moment of cinematic truth came at 16, when she slid into a grimy art-house cinema and saw Antonioni's L'Avventura. Anna Magnani was her pin-up - ''The greatest actress of all for me, absolutely, my god yes'' - and Italian cinema her benchmark. ''Fellini you could maybe say was sexist, but somehow the women in his movies … I can recognise them as people.'' She still defines herself as a European actor, even after many years in the Californian sun.
Actually, the fact she is still an actor at all pleases her enormously. People perceive her as having a late flowering but, she says, it doesn't feel like that from the inside.
''I've been incredibly fortunate, so fortunate, that I've managed to stay alive and still working. I just see it in those terms … I'm always saying to my husband, 'I'm going to stop working, that's it, I've done my stint, it's over.' And he says, 'Oh yeah, oh yeah, right - because I know next I will hear, ''It's a very good part, darling, they've asked me to do this and it's a really good part''.''' She laughs. ''And a good role, I'm afraid, I can't resist. It's terrible, but I can't.''
■ Hitchcock previews at Moonlight Cinema tomorrow and opens on Thursday.