Gordon Brown is known as many things - Chancellor of the Exchequer, for one - but film critic is not one of them. However, he added that job title to his CV when, in Edinburgh last month, he attended the world premiere of The Girl in the Café, Richard Curtis's new film about the G8 summit.
Outside the Cameo Cinema in the Scottish capital, Brown said: "I am here because this film is about the G8; it is about international development, and it is about the cause of making poverty history, and I fully support that."
OK, so the Critics' Circle may not be welcoming the Chancellor into its hallowed company just yet, but Brown is exactly the sort of mover and shaker Curtis and his fellow producers are hoping to reach. "The issue of extreme poverty is a matter very close to Mr Brown's heart," says Hilary Bevan Jones, the producer of the film, which will be aired on BBC1 tomorrow week. "The impression I got was that he thought the film was powerful. The more people in positions of power are able to see this film, the better."
Curtis, who is executive producer as well as writer on this project, asserts that The Girl in the Café is the film "of which I'm most proud" - and with the Live8 concerts and the planned protests surrounding the G8 summit at Gleneagles next month, it could scarcely be more topical.
The drama represents a union of the two causes with which the writer of Four Weddings and a Funeral, Notting Hill and Love Actually is most strongly associated: comedy and charity.
Showing as part of the BBC's Africa season, the film centres on Lawrence (played by Bill Nighy), an emotionally repressed civil servant who has no life outside of his work for a charismatic Scottish chancellor (Ken Stott). One day, however, Lawrence's meticulously structured existence unravels when he goes for a cuppa in his regular café and falls for an alluring yet mysterious young woman, Gina (Kelly Macdonald).
He and the girl in the café strike up a stuttering yet touching relationship, studded with Curtis's trademark one-liners. The besotted Lawrence soon asks Gina along to the G8 summit as his guest, and at this point this drama morphs into something altogether weightier: it moves from rom-com to rad-com.
Keen to see the achievement of the Millennium Development Goal to cut global poverty in half by 2015, Lawrence tells the unworldly Gina that "eight men in one room could literally save hundreds of millions of lives".
Gina undergoes a rapid political education - to the extent that she interrupts a speech by the Prime Minister (Corin Redgrave) by clicking her fingers every three seconds (the gesture used by Curtis for the Make Poverty History campaign to indicate how often a child dies needlessly).
It is undeniably potent stuff, which deftly blends belly laughs with belligerent politics. It underlines the words of Lorraine Heggessey, the former BBC1 controller, who commissioned the £2m film: "The Girl in the Café is a great way to get BBC1 viewers thinking about the summit. If anyone can make a romantic comedy about the summit that engages a mainstream audience, Richard Curtis can."
The writer is taking a break from editing with a well-earned cup of tea. "Will you forgive me slurping this tea? I've been desperate for it for ages," he says, turning it into a typically self-deprecating joke. "You could write: 'Richard Curtis has an unfortunate mouth disease which means he makes these slurping noises. He is curiously brave to do an interview with it.'"
I start by playing devil's advocate. Does Curtis believe that one humble film can alter anything fundamentally? "Wow, that's a big one," whistles the writer and co-founder of Comic Relief. "Films can change things. Look at Cathy Come Home, a much more important piece of work than this. That led directly to the setting up of Shelter."
Curtis, who is as sharp and witty in person as he is on paper, expands on this. "Almost all political movies tend to address issues retrospectively. This year, for example, there have been three films about Rwanda on the10th anniversary of the massacres. People feel more comfortable with political issues when they're in the past. But you can confront them in the present. Look at Jamie's School Dinners. That will change what all our children eat. So the more power the media has, the more responsibility it has to address current issues and try to effect change."
After filming, Nighy is unwinding in a London hotel suite. He is in high spirits, joking that he is prepared to use any means to win me over. "We've got a bed here, James, if we need to use it!"
Like Curtis, the actor reckons: "Films can influence things. If you're trying to explain something on page 27 of an agenda, you can soon lose people. But if you hand them a DVD, order them a sandwich and say, 'Take a look at this,' you've immediately got their attention. If you can then deliver your message in a way that's powerful and personal and yet universal, then you're in pretty good shape. Working on this film has already changed me in that it's given me a new perspective. When one considers the tragedy besetting Africa, one's own problems pale into insignificance."
The actor, who has gained a global profile on the back of working with Curtis on Love Actually, continues: "The example of Richard and many other people working on the Make Poverty History campaign has had a powerful effect on one. It makes you very grateful for the opportunity to contribute in some way. I'll become more involved now. Actors who have any degree of conspicuousness are not short of opportunities to try to spotlight issues like this."
Bevan Jones has collaborated with Curtis since she was a floor manager on Not the Nine O'Clock News in the late 1970s. She, too, believes passionately that films can change things. "May 33, the film I produced last year about a woman with dissociative identity disorder, had an effect in changing the rules about ritual abuse," she says. "Following the film, the police, who previously wouldn't accept that it happened at all, introduced a training course that recognised the effects of ritual abuse. I'd like to think our film changed their minds.
"In the same way, I believe The Girl in the Café could effect change on a number of levels. I hope it affects the outcome of the G8, but I also hope it makes people stop and think. How would you feel if you had to explain to someone face to face why you did nothing to stop their people dying?
"In the film, the Prime Minister says, 'We cannot allow this casual holocaust to take place on our watch.' Later on, in the most powerful line in the film, Gina says, 'Does it matter whose child it is?' It's a horrendous thing to have to choose. Thirty thousand children are dying needlessly every day - that's the equivalent of a British town. It's difficult to grasp the sheer scale of it, isn't it?"
But isn't there a danger that viewers might be put off if they feel they're being force-fed politics? There was, after all, quite a hoo-ha when the New Year's Day episode of Curtis's sitcom, The Vicar of Dibley, closed with footage of two African orphans over the caption "this year politicians could change this", and the seven main characters wore white armbands in support of Make Poverty History, the campaign of which the writer is a driving force.
"I'm not worried people will complain that The Girl in the Café is overtly political," says Curtis. "You've only got to think about that notion for a second to see how crazy it is. I'm not putting this in the same league, but two of my favourite films, Missing and The Killing Fields, are political and human at the same time."
Curtis, 48, has been fascinated by Africa since he visited Ethiopia after watching Michael Buerk's landmark BBC news reports about the famine there 20 years ago. The human suffering he witnessed led him to set up Comic Relief. "It was very much a feeling that it wasn't any use feeling bad and sentimental. One should just get up and try to do something."
The writer still feels as passionate about the continent - and as pragmatic. "In many African countries now, the mortality rate among children under the age of five is down to one in four. I've got four kids and so has Tony Blair. Don't ask me to choose."
Curtis, who is also heavily involved in planning Live8, says he is inspired by the fact that the British public really does care about this issue. "People are always saying that this is a non-political and disengaged generation, but I don't think that is the case. This is something we believe people from right and left, old and young can unite on. Through Comic Relief, the British public has given £200m to Africa. People are passionate about it. They would like to see their passion reflected by politicians."
Curtis regards The Girl in the Café as "a marriage between the two halves of my life". He continues: "I've never seen much contradiction between the Comic Relief side and the Hugh Grant side. If I was going to start writing about this issue anywhere, it would be logical for me to start with a love story. If Quentin Tarantino did it, it would start with the decapitation of the Prime Minister's wife!"
In The Girl in the Café, the rom-com is a sort of Trojan horse concealing what Ben Elton, Curtis's co-writer on Blackadder, used to call "a little bit of politics". "First and foremost," Curtis muses, "the film is trying to involve viewers emotionally in the relationship between these two people. Then, and only then, it's trying to pass those emotions on to political issues. That mirrors what happens to Gina. She thinks that she most needs love, and then she realises there might be something even more important."
The writer concedes that there was a risk that the character might appear as sort of human placard for the writer's views. "If there was a problem with the film, it was that Gina might be read as a political activist or someone who doesn't represent normal people," Curtis admits. "But Kelly Macdonald has this guileless honesty, so that when she starts talking about the issues, we believe her. She defused what was a danger because she has such humanity and simplicity."
He goes on to reveal that there is much of himself in the character of Gina. "I believe it's sometimes quite an advantage not to be that well informed," Curtis observes. "If I identify with one character, it's Gina rather than Lawrence. I have a lot of concern about the problems without a deep understanding of the practicalities of how they could be solved. With her, I was writing from the heart."
Curtis was undoubtedly helped by the casting of Nighy, just about the hottest property in British TV right now. "After Love Actually, I was very keen to work with Bill again," Curtis recalls. "I thought that in real life, he's sometimes quite diffident and awkward, as well as funny and idiosyncratic. He's a serious, proper actor, and I wanted someone who'd get the depth of Lawrence's unhappiness."
Nighy, in turn, was delighted to team up with Curtis once more. "Richard has the rare gift of being able to mingle comedy with tragedy," opines the 55-year-old actor. "Hardly anyone else can do that, which is one of the reasons why he's so successful."
Nighy, who is about to jet off to the West Indies to play the baddie alongside Johnny Depp in the two sequels to The Pirates of the Caribbean, adopts an attitude of wry amusement to his new-found fame. He is tickled, for instance, that two female characters of a certain age were recently raving about him in an episode of The Archers. "Four friends who are normally very relaxed about my career texted me to say, 'Did you know you're on The Archers?' That brought a whole new world of responsibility. I have to agree that being mentioned on The Archers is a sign that I have truly made it!"
Nighy hopes that the film will pull off that most difficult feat of making us laugh and think at the same time. "Jokes are useful," he concludes, "because information travels very well in joke form.
"So laugh, please. Put in your article that if you don't laugh every couple of minutes, you can call me. I'll give you your money back, or I'll come round and tell you a joke. 'Who is it?' 'It's Bill Nighy. He says he owes you a joke!'"
'The Girl in the Café' is on BBC1 on Saturday 25 JuneReuse content