When Sienna Miller met Tippi Hedren

Last week Sienna Miller was starting to think about her first Christmas as a mother. Her voice was freighted with all the emotional weariness of a woman who knows the particular joys of surviving for too long on only an hour or two's unbroken sleep. Her daughter Marlowe, now four months old, was on her lap. A good deal had happened since I interviewed her in the summer about her forthcoming TV movie The Girl, in the company of "the girl" in question, Tippi Hedren, the actor, who was muse and obsession to Alfred Hitchcock in the 1960s.

As well as becoming a mother, and travelling to the States for the American launch of The Girl with Hedren – with whom she seemed to have struck up an uncommon bond, based on a kind of glamorous sisterly solidarity across the decades – she has been working. Until recently she was on a film in Pittsburgh with Bennett Miller, director of Capote and Moneyball. "Though I know I had promised myself not to work so soon after the birth," she says, "it was too good an opportunity to turn down." As a result Marlowe "has been on about 15 planes already", along with her frayed-nerved mother and her father, actor Tom Sturridge.

Miller had also been getting her head around the substance of the Leveson report. This time last year she had been one of the starriest witnesses to the inquiry, describing in detail her harassment by the paparazzi – "like living in some sort of video game where they pre-empted my every move" – as well as the hacking of her phone, for which she had received £100,000 in damages from News International. I wondered what she had made of the outcome.

The report itself was spot on, on the whole, she thinks. "But then," she says, "I feel it was completely let down, as always, by the negative response of the government. Once again an inquiry has been made to look like an enormous waste of time and money…" She supposes it was predictable. "Of course it was going to end that way. Why are we surprised? The good thing is I feel things have changed already. I doubt anyone would be stupid enough to hack into anyone's phone again. But I have to say the government's response really angered me."

I wonder if the experience of motherhood had given her an even greater desire to police the boundaries of her privacy, and those of her family. "Well," she says, "I don't have that in England any more: I am fine. I still have an injunction against the paparazzi, which I have had for four years now."

Few actors have been as clear as Miller over exactly where the public and private boundaries of the life she has chosen should lie. In this she shares the spirit of Hedren. Certainly it was one of the things that attracted her to the script of The Girl and gives an extra edge to her performance. The film, which is a drama highlight of the BBC's Christmas season, explores the stalker-like and controlling relationship of Alfred Hitchcock toward Hedren, who starred in his films The Birds and Marnie in the 1960s, and whose career he both created and destroyed.

Speaking to Miller and Hedren together in the summer had offered me powerful evidence of their shared qualities. Both are frank, collected presences, with eyes that hold your gaze. They had enjoyed dressing up for the Observer's photo shoot, trying on clothes and chatting, both effortlessly scene stealing. Having played Hedren in the film, and experienced at first hand, as it were, some of the claustrophobic sexual aggression exercised by Hitchcock (played with uncanny brilliance by Toby Jones), Miller seemed slightly in awe of what the older actor had endured and how she had survived to tell the tale. Hedren, for her part, seemed to see a lot of her younger spirited self in Miller.

They had met first at Shambala, a reserve for unwanted zoo animals – tigers and lions among them – that Hedren established 40 years ago in California. Thereafter Miller would call up Hedren from time to time from the film set, just to ask how it had felt for her at different key moments of Hitchcock's bullying. "There were lots of details," Miller says, "but the most useful thing she told me was that she had made a vow that whatever happened she would never make him think that she was open in any way to that kind of attention. To keep that with no ambiguity…"

I wonder if Miller had drawn on some of her own experiences of a very different kind of harassment – from the media, being chased down the road by 15 large men with cameras every day – to give her something of an insight into how under siege Hedren must have felt.

Miller says she didn't directly make the connection. "I hadn't been exposed to anything like that. It would be an immediate lawsuit today. But the lasting effect of my experience with paparazzi and that feeling of being constantly harassed is buried pretty deep in my psyche. So maybe that is something I could have accessed. I certainly didn't sit down and think: 'I got stalked, so I know what it feels like.'"

Hedren was 30 – Miller's age – when Hitchcock had talent spotted her in a TV ad and seen enough to cast her as the lead in The Birds, his follow-up to Psycho. As the script of The Girl, on which Hedren consulted, makes clear, the director's predatory mind games with his star began almost straightaway, with her screen test. What Hedren subsequently endured in the making of The Birds – cruelties which culminated in her having live seagulls and crows thrown at her in an attic for five consecutive days of filming – have long been an open secret in Hollywood. The Girl explores the off-screen darkness in Hitchcock's psychology which fuelled some of the most chilling and memorable scenes in the history of cinema.

How much of this did Miller know before she read the script?

"I had seen The Birds, of course, but I didn't know the whole backstory," she says. "I had no idea. I assumed that Hitchcock was mildly misogynistic. But nothing like this. And I hadn't seen Marnie at all until I got the project. But watching it now it is such an extraordinary film. At the end of it you are willing Tippi's character to get with this rapist. You are relieved she is ending up with this man who raped her. It is so manipulative in that way."

Hedren has no doubt the manipulation was a fantasy of the director. "It was really Hitchcock, that character," she says. "I mean, I always assumed so. The writer didn't want to do the rape scene, and Hitch fired him because of it. He insisted on having it done."

That film was the last time Hedren worked with Hitchcock; she knew she needed to escape. It was during Marnie that he became insanely possessive of her, she says. "If he thought I was dating someone he would confront me wildly about it," she says. "He had me followed. He had my handwriting analysed. He warned both Rod Taylor and Sean Connery [co-stars in the film]: 'Do not touch the girl.' It was a constant need to control. Always insisting on a glass of champagne after work when I wanted to get home to my daughter. Always trying to be alone with me…"

Hedren was a single mother when she made both films for Hitchcock; her daughter grew up to be the actor Melanie Griffith. When Hedren refused to work with the director again he held her to the contract she had made with him, paying her $600 a week to do nothing for two years, refusing approaches from other directors – including François Truffaut – who wanted to cast her in their films.

How commonplace was such behaviour in the industry at the time?

"It was very commonplace," Hedren says. "The stories were legion." The director's defence of his behaviour was that he was "doing whatever it took to turn you into a movie star".

The most extreme example of that was the attic scene in The Birds. Miller experienced a controlled fraction of what Hedren was forced to go through, but it was enough to imagine how it must have been: "There were a few real screams in there, but you know, I had live birds thrown at me for an hour in this confined space, which in itself was pretty brutal – Tippi endured it for five days."

Even so, Miller was in the early stages of pregnancy at the time. Was she worried at all about the effects of the stress?

Miller smiles. "I was pretty delirious," she says. "I was filming during the first trimester. It was actually quite distracting. The tiredness was quite debilitating. And you can sometimes use some of that in your acting. But no, I always felt in a totally protected environment."

Hedren never experienced anything like that feeling. In the famous scene where she is attacked by the birds in a phone box she had been told that the box had shatterproof glass; in fact when the mechanical bird hit it and the glass shattered, she spent all afternoon having fragments of glass pulled out of her face. The attic scene was Hitchcock wanting to push her beyond breaking point.

"When I look back at it I can't believe that it went on for so long," Hedren says now. "It was just such a very mean thing to do. By the end I was so tired. I had never been so tired in my life. I took care of Melanie that weekend, but I don't remember anything about those days until I got back to my own bed. I just slept – no one could wake me. Hitchcock had a very strange mind. My doctor told him I had to rest for a week. And Hitch said: 'How can she? She is all we have to shoot.' And the doctor said: 'What are you trying to do? Kill her?' We shot The Birds for six months and I had one afternoon off."

Was the attic scene the point when she realised she was in a relationship with her director that she had to get out of?

"It was beginning then. The constant, constant staring at me. Watching my every move. Even when he was talking to someone else."

Has Miller had any experience of that?

"I think all women have to a small degree. You can be on a tube or a bus and someone can stare and you can't stop them. But when that person is running your life and your career, then it becomes a difficult thing to navigate. You know as a woman when something is not right."

Hedren felt unable to speak up about the harassment at the time, even though everyone on set was aware of it – including, she says, Hitchcock's wife, Alma Reville. "She was around. She said to me one time: 'I'm so sorry you have to go through this.' But she never, it seemed, tried to get him to stop…"

The closest Miller ever came to experiencing that kind of discomfort, she says, was in an audition a couple of years ago. She doesn't want to name the director, "but he had an actor in to read opposite me. We hadn't even been introduced. And the director told this guy to start seducing me and kissing my neck while we read. It was so weird. Eventually I just said: 'I can't do this.' And, of course, I was told I was difficult and all that. But I felt really violated by letting it go on for 10 minutes to try to get a job. And, of course, I didn't get the job. But it felt so old-fashioned, so inappropriate."

Aren't director and actor relationships always in danger of being slightly obsessive?

"If anything," Miller says, "I have always experienced paternal behaviour – protective, slightly possessive, even. But not anything like this. I think Hitchcock was of a different ilk, and in any case it was far more acceptable, if that is the word, to behave like that than it is today. I suppose these people create these situations for their own amusement. And that comes from a lack of morality…"

Could Hitchcock have made the films without the cruelty of that relationship?

"I can't answer that question. But what I do know is that I think he is getting his comeuppance with The Girl. Though with Toby's performance you also empathise with him, I think. I mean, can you imagine being trapped in that body, when I swear he thought he looked like Cary Grant?"

Times, Hedren and Miller both believe, have changed, and for the better. Blonde film stars will always be required to be fantasy figures in some way, they say, but Miller is coolly certain that "nowadays we are far more able to achieve things without feeling indebted to some man who essentially wants to control and possess free-spirited women … There is," she says, as her older friend knows only too well, "a lot more to life than being puppeteered by creepy men."

The Girl is on BBC2 on 26 December at 9pm