“There’s no reason she should be jealous of this woman who’s been dead for 50 years,” says the British-born Rampling, also a long-time star of French and Italian cinema. “She’s just destabilised by Geoff’s reaction to this, and then by her own.”

To some people, 50 years may feel like infinity. To Rampling, it is roughly the time that she’s been famous: her first leading role came in the comedy Rotten to the Core (1965), when she was 19. “Has it [been 50 years]? I’m not counting,” she giggles. “Don’t bother with that. I don’t like these kind of details, because they sort of compress time. I don’t want time compressed.”

According to Rampling, the earliest role that she “really registered” was in Georgy Girl, a fashionable comedy from 1966. “There I was a bit scared,” she recalls, “because I saw things [on screen] that I didn’t know were in me – that is to say that you are sort of expressing things. I saw a whole layer of things that actually were coming out but I didn’t even know I had in me, and it scared me.”

Shortly after that, Rampling’s distinctive aura had earned her the nickname of “The Look”, which was first spoken by the Italian master director Luchino Visconti during the production of The Damned (1969), and subsequently recorded in print by Dirk Bogarde in his preface for a book of photography that Rampling did.

“I have a whole lot of photographs [at home] – the work photographs since I was 17, and from different books,” she says. “And I took photographs for a long time when my kids were young. I’ve loved taking pictures for about 20 years now. I would take black-and-white pictures of anything I like the look of. I’m very attached to photography – and to what photography means in our lives.”

In one of the many poignant scenes in 45 Years, Kate remarks on how few photographs the couple have kept at home, only to be reminded by her husband of the reason they took them off. “When you heard yourself saying the line, there’s something very melancholy about it,” Rampling says. “I think with the photographs we have chosen to display, it illustrates a lot – not so much about who we are, but what our lives have been, in a way.”

When I ask if Rampling feels her early experience with social realist cinema has lent anything to her part in 45 Years, which is set in Norfolk on the east side of England (close to where the actress grew up), she offers me a wider explanation. “I’ve always seen my cinema life as being associated to my life. I’ve always wanted to do films that were sort of on that same journey,” she says.

“I didn’t want to just be acting in films. I wanted to, in a rather grand way – not make social statements, but make films that were engaging in terms of the emotional journey of human beings and behaviour. I used to love that with films: like Roberto Rossellini and those Italian films, they affected me hugely. And yes, this film is very much on that journey.”

Fans of the actress would be well aware that, after temporarily reducing her acting output in her 40s and early 50s, Rampling has shown a renewed hunger for work since she took the lead of Francois Ozon’s grief-tinted drama Under the Sand (2000), when she was 54. Her next collaboration with Ozon, Swimming Pool (2003), only sealed her resurgence as the most exquisite of performers.

“This is the kind of language that I want to speak in cinema,” she says of the Ozon partnership. “I hadn’t really had too many chances to find somebody who’s gonna do it with me.”

Rampling then volunteers that she sees a similarity between Marie, her character in Under the Sand, and Kate in 45 Years. “Marie, to me, could almost be the same woman. She could almost be the younger version of Kate, in a subtle way – but if you see what I see, the language is the same. It’s like she has the camera on her shoulder. You’re actually inside Marie’s head, and you’re inside Kate’s head.”

Or could it simply be that Rampling remembers her better roles more vividly than she does the rest? “Yeah, a lot of the stronger ones stay with you – they really are a part of you,” she says.

“With this kind of acting, you’re not actually putting on a costume and a hair and a wig or whatever and going out and pretending. You actually are – but you’re adapting what you are to somebody with a different name and a different life – but it’s very much essentially you. So they do stay in you. And they’re my children; they’re all my best friends,” she says with a laugh.

Although she may give the impression of being intensely private about her family life – she kept the 1967 suicide of her eldest sister, Sarah, a secret for more than two decades – journalists who have interviewed Rampling would often be surprised by her candidness in general. Once in a while, that leads to unwanted attention.

In January, her claim that the boycott resulting from the Hollywood diversity controversy – over the lack of nominations for African-American actors – is “racist to white people” was taken by some to denote her unchecked white privilege. Rampling, naturally, declared that she was misinterpreted.

Has the actress ever been fed up with the intense scrutiny of the showbiz life? “Well, I think we’re lucky in our business so we can’t say that,” she says. “Most people with jobs have to keep going at it; we can sort of step back from it, and that’s really lucky. We can say, ‘Ah, no, I’m gonna just take six months off. I’m just not gonna answer the telephone.’ And people say, ‘But aren’t you scared?’ ‘They’ll call eventually’.”

Given her steady output since the early 2000s, Rampling’s relaxed approach certainly seems to be working. “Anyway, I have always allowed myself to step back. Even if nobody ever calls again, I’d always do that,” she says. “I have never had a very busy schedule. I’ve never jumped from one project to another. I don’t need that. It’s not my style.”

45 Years opens on April 14