Earlier this year, when a Hong Kong charity called The Hub began planning its fourth annual ball, certain things fell into place quite quickly. They had a date: Friday, October 23. They had a venue: the Grand Hyatt ballroom, in Wan Chai. They had a theme: Hollywood Goes to the Races. They had a sponsorship package: peak sponsors (those who donated more than HK$250,000) were offered benefits and opportunities that included "exclusive meet-and-greets with the Hollywood VIP guest of honour". What they didn't have was the Hollywood VIP guest of honour.

The Hub is fairly new on the Hong Kong scene. Two Hong Kong-based Australians, David Boehm and Bruce Stinson, who've been here for more than 30 years, decided it was time to give something back. They approached Bill Crews, whose Exodus Foundation in Australia works with the homeless and those in need; and now The Hub operates "as a children's support concept" under the aegis of the Bill Crews Foundation.

The idea is to provide a safe, comfortable environment in which underprivileged children can do their homework, have access to tutors and counsellors, be encouraged to develop new interests and have some fun. In 2012, the first Hub fundraising ball was held to raise money for premises. (That year, Hong Kong's Commission on Poverty estimated 209,000 children under the age of 18 lived below the poverty line here, a number that has certainly increased.) The following year, with the help of the Rotary Club of Kowloon North, The Hub opened in Sham Shui Po, officially Hong Kong's poorest district.

Boehm, The Hub's chairman, is an accountant by training "but these days, I'm in investment - natural resources and property".

Natural resources, in this case, means mining. One of his business partners is billionaire Robert Friedland, founder of Ivanhoe Mines and a man who's had an interesting career extracting the natural resources of countries such as Cambodia, Myanmar and Mongolia, not always to the delight of the locals. (According to Steve Jobs' biographer, Walter Isaacson, Friedland was also, briefly, a guru to Jobs when they were both students in Oregon, in the United States. Friedland was then in charge of an uncle's 90-hectare apple farm outside Portland, where Jobs would spend his weekends with Hare Krishna practitioners, pruning apple trees and moodily wondering where his life was heading.)

“I’m too much of a people-pleaser … I did really well at school, I was the brainy nerd. But I created this persona where I could be prettier”

Five years ago, Friedland and an American producer called John Penotti established Ivanhoe Pictures to co-finance and co-produce local language films in Asia, particularly China, South Korea and India. Penotti has been on the Hollywood scene for more than 20 years. You won't necessarily recognise his stable of films ( In the Bedroom, Awake, Frozen - no, not the Disney one, the one about three skiers stuck on a ski lift) but he's a hub in his own right: his contacts are sufficiently stellar that after he told fellow producer Charles Wessler (Dumb and Dumber, There's Something About Mary) about The Hub, the latter arranged for American actress Carrie Fisher to appear at last year's ball. (Boehm likes to joke that appearing at The Hub ball obviously did wonders for Fisher's current career; she has reprised her most famous role, as Princess Leia, in Star Wars Episode VII, which is to be released next month.)

This year, however, was a little tricky. It can be difficult, after all, to extract actors from the bedrock of Hollywood, transport them thousands of miles and insert them into an alien seam. Various names came and, regretfully, went. Then Penotti, who has a puckish face, a curly quiff and what New York magazine describes as a "preternaturally calm" demeanour, had an idea: Heather Graham.

"I'd met her a bunch of years ago through work," Penotti explains, in the Chief Executive suite at the Grand Hyatt, where we've gathered about two hours before The Hub's ball is due to begin. "A mutual friend reminded me of Heather's interest in Asia and children's charities in Cambodia. So I hoped she'd be similarly supportive. We asked her on Thursday and she said yes on Thursday - the same Thursday. That's how keen she was."

When was that? "Last Thursday."

Wasn't that cutting it a bit fine?

"I told David to relax and he did. David never sweats," laughs Penotti, while Boehm, sitting alongside in black tie, indicates relief. "This was very close for comfort but it's hard for actors to look into the future. Heather's simple, she's kind, she has a wonderful heart, a great spirit. I felt we needed someone who shares a sense of giving and a sense of warmth."

Meanwhile Graham, who's having her photo taken behind the two men, smiles and shifts position on cue. She flew in from New York that morning. Not by the smallest jetlagged quiver does she indicate she'd rather be somewhere else. Her apparent enthusiasm never falters. If it's possible to sum up someone's nature in a single word, based solely on a 40-minute interview with people trotting to and fro, hers would be: obliging.

Graham has built an entire cinematic persona based on availability. The roles with which she's usually associated are porn star (twice - Boogie Nights, The Guru), stripper (twice - The Hangover Part I and Part III), a bangtail - as prostitutes were called in Jack the Ripper's London (From Hell) and a CIA spy named Felicity Shagwell (Austin Powers: The Spy Who Shagged Me). Even when she's playing a web designer called Alice, as she does in Killing Me Softly, she somehow winds up in an erotic thriller. (Local relevance: this was Beijing-born Chen Kaige's one and only English film. It has a critics' score of 0 per cent on the Rotten Tomatoes website.)

She is, as she later admits, a people-pleaser. You sense this immediately because she seems incapable of letting anything in her field of vision go uncomplimented. Pleasant though this is, the scattergun nature of her praise rather stifles the effect. It's the kind of behaviour that's honed at school: a lovely girl's way of deflecting hostility.

"Pretty dress," she murmurs coming into the room and hovering politely until she's told where to sit. (Seeing Boehm, with whom she had lunch so that he could fill her in about The Hub, she remarks, to his surprise, "Oh, he's incredibly cool.")

Now 45, she looks about 28 and - this is the first thing every woman has subsequently asked me - shows no discernible evidence of Botox. She's never been a sun-worshipper, which helps; but perhaps the most youthful thing about her is that eagerness to engage.

Complimented on her own dress - an abbreviated black two-piece clasped so fleetingly at front and back that the impression is of slices of white torso arranged between white legs and white arms, all long and toned - she says, "It's Nicole Miller, she's a friend of mine."

Then she leans forward and compliments Hong Kong: "Wow, this is such a pretty view … What are they building down there?"

We, briefly, discuss the Wan Chai bypass. Graham passed through Hong Kong once, in the mid-1990s, when she was travelling round China with her sister, Aimee, also an actor.

"It's so fun to leave what's familiar, and it's such a sophisticated city," Graham says, and offers a slightly hesitant opinion: "It's kind of an Asian New York."

Earlier in the day, Penotti and Graham headed out to find Kowloon Walled City. (Asked why, Penotti simply says that he's interested; a later Google check will reveal that Ivanhoe Pictures has bought the film rights to The Walled City, a young-adult novel by Ryan Graudin that's been described as a cross between The Hunger Games and The Maze Runner.) They ended up, however, in Kowloon Park. As Graham will be leaving for Cambodia first thing in the morning this means she hasn't actually visited The Hub, which, in the circumstances, seems a little odd.

"She could have gone sometime during the day," Boehm agrees. "But the kids aren't there then - they're there in the evenings and at weekends. Promise you'll come next time!"

"I promise!" Graham says, winningly.

Earlier, in the lift, Boehm, who was clutching an envelope labelled Phnom Penh Hotel Voucher, said, "The main reason she's here is for the ball tonight but the incentive was, 'We'll arrange for you to get to Cambodia'. The quid pro quo for her is she gets to support the charity close to her heart."

Which is the Cambodian Children's Fund (CCF), set up by another Australian, Scott Neeson (no relation to Liam), who was a highly regarded Hollywood film executive until, one day in 2003, he saw the Steung Meanchey rubbish tip outside Phnom Penh and children scavenging upon it. The following year he moved to Cambodia and the CCF, which has been featured in Post Magazine, now offers education and medical care to 2,500 children.

Graham sponsors five of them: two teenagers, a 10-year-old, a nine-year-old and a six-year-old.

"It's fun. I email them, one of them wants to be a doctor. It's inspiring - being there blew my mind; that's why I'm excited to come back. To be honest, it's shocking that people are doing such amazing things. It's great to have events like these, I'm excited to learn about this charity tonight. The newspapers are so depressing - you know what they say, 'If it bleeds, it leads' - but they should do more of these stories."

Does she read a paper every day? "You know - I don't. It's too depressing."

Given this, I'm curious to know when she first encountered poverty. Graham looks mildly agonised.

"My dad was in the FBI and we were transferred around but we always lived in suburbia. I never, ever saw homeless people there. But the level of poverty in Cambodia is super-duper. It's kind of mind-blowing."

I've read about that transient upbringing, and also that it was strictly Catholic. She was offered one of the Heather roles in the 1988 film Heathers, which sounds wonderfully appropriate except that her parents - from whom she's famously estranged - considered the script deeply inappropriate and refused to allow it. Her subsequent choices would appear to have been a career-long riposte to such control. (I'm totally available!) But the claws of Catholic guilt sink deep and maybe that's what motivates her.

"That's funny," she says, faintly, hearing this theory. There's a little pause. "You know, I have to say the more involved I get, it makes me feel really happy."

Would she do an Angelina?

"What do you mean? Oh … adopt. You're not allowed to adopt in Cambodia." (Jolie adopted Maddox in 2002, but subsequent concerns about human trafficking led to crackdowns by international governments and Cambodia has since suspended its adoption programme.)

What about other countries? Graham, who carefully researches the charities to which she contributes (and, like a biddable pupil, starts to recite a list of them - Oxfam, Women For Women, the Fistula Foundation - until I ask her to stop), muses on this generally.

"India … if I give money to a kid begging, it might go to a weird, horrible person. Like, if you saw Slumdog Millionaire, there could be some horrible pimp propagating the system. You have to be careful."

Boehm is hoping The Hub - which was jointly established in Bangkok in 2011 by Childline Thailand, Crews and Boehm, and runs a youth centre there for "children in distress and street kids" - will expand to Cambodia. It's possible, Boehm says, that there could be synergy with the CCF.

"I'm hoping to hook these guys up!" Graham cries. "There are a lot of cool Australians out there. Did you have a grand plan, David?"

"No, no," says Boehm. "I just thought I'd help. We'd stumbled upon an opportunity in Bangkok and then Bruce said, 'We live in Hong Kong, we should do it here.'"

In order to fly to Hong Kong at short notice, Graham has had to abandon her "work of passion". She has written and directed a film called Half Magic, currently in post-production.

"It's very empowering to women," she says. "It's funny, it's a female point of view about sex and relationships that I don't see reflected in movies."

That may have been true 15 years ago but, surely, less so in this era of Lena Dunham, Amy Schumer, Melissa McCarthy? Graham agrees, though - obviously - there's room for more.

If you want to help kids, that seed of intention can grow into reality from believing it. I want to put something out into the world that's positive

"This is a female raunchy comedy but it's also soulful and short. I'd love you guys to see it! It's saying that if you believe in magic, then there's magic. And" - Graham graciously seizes her chance - "if you want to help kids, that seed of intention can grow into reality from believing it. I want to put something out into the world that's positive."

On her Twitter page Graham says she loves telling dirty jokes so this seems like a good moment to hear one. "Now?" Yes. After about three seconds, she begins demurely: "Two sperm are swimming. And one's, like, 'I'm so tired, are we near the uterus yet?' And the other one's, like, 'The uterus? We haven't even reached the oesophagus yet.'"

I'm not sure how that's going to read on the page but listening in person, it's extremely funny. At least half the impact is the contrast between the words and Graham's apparent hello-trees-hello-sky, Wonderland innocence; this, of course, is why - mostly - male directors love to place her in perverse environments. (Even her few parental roles have been skewed: she was Danny DeVito and Arnold Schwarzenegger's mother in Twins, and last year she played the notoriously unmaternal Corrine Dollanganger, from Flowers in the Attic, in three made-for-television films based on V.C. Andrews' original book and its sequels.)

Where did the joke-telling come from?

"I used to be in this acting class," she says. Was that the one where she met Adam Ant? Graham hesitates. "Hmmm."

She and the British singer dated in the 90s. In a 2002 interview with The Guardian newspaper, Ant described their life together in Los Angeles: "We were very much in love. I think I would definitely have stayed in that little place and been happy." But he had a breakdown (he has bipolar disorder) and, although he moved in with Graham when he was released from hospital, he eventually moved back to London in 1995. She went on to date a variety of actual, and rumoured, men - usually Hollywood connected - but has never married.

"That's very deep," she says, in a low tone after I read out Ant's comments about their relationship.

After a moment, she continues, and even though she's using the second-person pronoun, it's a first-person observation.

"You can't really help everyone … You can't help the people who can't help themselves." She pauses. "It's weird, you look at things and think, 'What do I have control over?' So it's good to be around people who can help themselves. You think, I can help this kid."

I tell her that I've watched some of her heroic chat-show appearances on YouTube, including the two occasions when she, literally, stood on her head at the hosts' bidding.

You can't really help everyone … You can't help the people who can't help themselves

"I'm too much of a people-pleaser," she remarks, softly. (Oddly, we're now both semi-whispering.) "Not all women have it but it's somewhat cultural. I did really well at school, I was the brainy nerd. But I created this persona where I could be prettier. I try and deal with that in my movie."

A trio of women connected to The Hub's ball enters the suite. Graham immediately cries, "Everyone's so glamorous tonight!" One of the women kneels next to her and produces a handful of glittering accessories. She's from Hattons Diamonds ("the first pan-Asian online diamond boutique selling GIA-certified hi-quality diamonds at the lowest prices in the world"), one of the ball's sponsors, and she's hoping that Graham will wear a bauble or two.

Graham looks (politely) aghast, "But how will I get it back to you? I'm leaving early in the morning." The woman assures her she'll be present at the ball all evening. After some amiable discussion concerning a necklace that Graham doesn't think will go with the high neckline of her dress, she chooses a bracelet so delicate you can hardly see it.

Later, as the lobby fills up with ball gowns and jewellery and the occasional fur, her pale legs and arms can be glimpsed scissoring through the crowd. In the Nicole Miller number, she's possibly the simplest-dressed female at the event. There are no minders with her, just another woman - Alison, her closest schoolmate from her days in Agoura, California.

"The guys let me bring a friend," she explained, earlier. "I'd been telling her about Cambodia and she wants to see the kids. She's a lawyer and she fights for special-needs kids in the school system.

"Isn't that amazing? I know! It's awesome."

For more information about The Hub, visit www.thehubhk.org.