"This woman never disengages from her life," beams Moore, her signature red hair done just so in the suite of a London hotel, "and I think that's pretty inspiring."
Born Julie Anne Smith on an army base in North Carolina, Moore had an itinerant childhood thanks to her father's profession — Peter Smith would later end up a colonel.
As a child, she moved 20 times and attended nine schools. Moore, who attended acting classes at school, has said that "it made me attach a very high premium to security", which might explain why she boasts one of Hollywood's longest unions — two decades — with film director Bart Freundlich.
They have two children, Cal and Liv, now aged 21 and 17. If on-screen, she is all kinds of evil, off-screen she is remarkably domestic. Or, in her words, "incredibly bourgeois". Or, "absolutely neurotic about cleaning".
Gloria is the kind of mess Moore could never be. But she is also a real, complex woman, and the actress relished every minute playing her.
Director Sebastian Lelio (A Fantastic Woman, Disobedience) made a 2013 version of the film, and Moore saw it, loved it, and lunch was arranged between her and Lelio.
"Right at the end he said, 'Well, I know that you don't want to remake this'," she recalls, "and I said, 'I would do it if you directed it', and he said, 'Well, I would direct it if you were in it!"'
The film is a rare portrayal of a middle-aged woman living her life, which isn't something Hollywood overindulges in. Does this representation matter?
"Oh, that matters a lot!" Moore exclaims. "Because we are rarely asked in cinema to identify with that person, right? So the fact that she happens to be a woman in her 50s who's happily divorced, to see someone who's that vibrant and that alive and engaged with life, and whose story is central, I think that's great. Because it's unusual."
It's also rare to see an older woman's sexuality on-screen. Gloria's relationship with Arnold (John Turturro) is awkward, furious, tender.
"They don't show older men, either," adds Moore. "I mean usually, when you think of movies, and an exploration of that [sex], it's usually with young people and it's a romantic comedy. There's not a whole lot of relationship-driven film right now."
Gloria does not spend all day bemoaning her fate as a middle-aged woman. It's just "the drama of ordinary life", says Moore, simply.
"I always feel like there's more drama in an ordinary day than there is in anything that we manufacture. Gloria's whole arc in Vegas is completely understandable, but you're just sort of ... gasp!"
Gloria's time in Vegas comes to a head when she wakes up on a sunlounger, with last night's dress on and one shoe missing.
Has Moore ever had a Vegas moment? She smiles. "Umm ... I don't think I would tell a newspaper!"
Moore tends to dodge controversy. Her parents, in fact, were dismayed when she settled on acting as a vocation. The reaction of her Scottish-born mother Anne, was: "Oh, Julie, why waste your brain?" They insisted she study acting as part of a "proper" degree. "Which is totally fair," says Moore.
"It didn't even seem early for me to make a decision about being an actor at 17. Now, I'm like, are you out of your mind?
"I don't know that I would have been as sanguine as my parents were."
It doesn't sound like this will ever be tested. Her daughter Liv recently worked as her PA on forthcoming film After the Wedding, directed by Freundlich, and was less than enamoured by the movie industry.
"Both of my kids are like, 'Why do people do this?'," she says.
She herself takes a realistic view of the industry. When I ask if she gets equal pay, she exclaims, "Oh, no! Definitely not," laughing at the absurdity of it. She explains that in independent films often she does because actors take a share of the profits rather than upfront pay.
"But in terms of other films, obviously it's hierarchical. So if there are people who have bigger parts and are bigger stars, they'll be paid more. But I think the question everyone is asking is, well, even if it is hierarchical, and you have actors of equal stature and equal parts, then they should be paid the same. It's very challenging."
Moore knows there is a long way to go, but she is not as cynical about Hollywood as you might expect.
The obvious, trite conclusion to all this is that Moore is that much-discussed thing, "a strong woman". True to form, though, Moore stays politely counter-intuitive; she respects the herd, but doesn't run with it. That much is clear when I ask if Gloria is a "strong woman" too.
"I don't think it matters," she replies. "Sometimes, there are all these adjectives about what you're supposed to be. I don't think people have to be strong. I don't think they have to be anything. I think you just have to be a human being."
