Julia Roberts - Has cinema's queen lost her crown?

Can Julia Roberts still "open" a movie? It's a question that will be answered next week when Roberts' new thriller/romance Duplicity (which re-teams her with Clive Owen, her costar in Closer) opens in the US and UK. Roberts hasn't exactly "retired" from the screen in recent years but, with three young children to raise, her priorities have clearly changed.

The 41-year-old star was in London earlier this week for the film's red carpet premiere in Leicester Square. It is strange to think that it was now almost 20 years since Pretty Woman (1990) had made her into the most bankable star in Hollywood. In an industry in which male stars have traditionally out-earned their female counterparts, she famously went on to become the first woman to break the $20m (£14m) salary mark for a film. Nor was her success short-lived.

In her 1990s prime, Roberts seemed almost unique. With her wraparound smile, lustrous hair and svelte figure, the former model looked as glamorous on camera as any star from the old days of the studio system. At the same time, she had an earthy, blue-collar quality about her (perhaps best exemplified in her Oscar-winning turn as single mum turned environmental campaigner in Erin Brockovich.) Moreover, she could act. Roberts was both likeable and capable. She could move seamlessly from romantic comedies to big budget thrillers, from period dramas to experimental movies.

However, Hollywood isn't sympathetic toward ageing stars who take sabbaticals from the screen. Nor is ageing a sensible career move. As Michelle Pfeiffer recently commented, "there is no question that the older you get, the fewer good roles there are".

The double standards are self-evident. Male stars from Cary Grant to Harrison Ford have been able to play romantic leads or action heroes even as they advance through middle-age. Meanwhile, the female stars are far more quickly put out to grass. From headlining studio films, they are pushed toward the independent sector. As they slip down the billing, they are given character roles or made to play dowdy matriarchs. Their former glamour is mocked or caricatured. One thinks of Gloria Swanson's Norma Desmond living in isolation and clinging to the memory of her forgotten celebrity in Billy Wilder's Sunset Boulevard (1950) or of Joan Crawford and Bette Davis catfighting in grotesque fashion in Whatever Happened to Baby Jane (1962).

There is no sign that Roberts is anywhere near these doldrums yet. Nonetheless, cinema's obsession with youth isn't changing. Meanwhile, the public's relationship with stars seems to be undergoing a transformation. For almost a century, stars have been the bedrock of the film-going experience.

"In the star, your producer gets not only a production value in the making of the picture, but a trademark value and an insurance value, which are very real and very potent in guaranteeing the sale of this product," a 1927 Hollywood business prospectus explained.

In recent years, there have been signs that this is being questioned. The bulk of Hollywood's profits come from the huge summer movies – effects-driven, comic strip spin-offs. These films may have stars but they are certainly not star-driven. It doesn't make that much difference which actor is wearing the spandex just as long as the CGI and the big set-pieces are up to scratch. The budgets for these films are huge but the money goes on spectacle.

Meanwhile, runaway successes like Danny Boyle's Slumdog Millionaire or teen vampire romance Twilight have broken box-office records without having any especially big names attached. This is the world into which Duplicity, being labelled as Roberts' "comeback" after her years away being a mum, is being released. Roberts is in a far stronger position than many other stars of her generation. She is a "player," a power broker as well as an actress. She has her own production company, Red Om Films, which means she can nurture and produce her own projects as well as star in them. These are films that are likely to turn up at festivals like Sundance and Berlin and to be given limited releases. They're not the blockbusters we've been used to seeing Roberts in. Nonetheless, the signs are that she will at least be able to exercise control over her career.

Roberts' name still carries weight. As The Hollywood Reporter noted of her recent indie film, Dennis Lee's Fireflies in the Garden (2008), "anything starring Roberts stands a chance". The film may have struggled to find distribution internationally but that hasn't stopped the actress from signing on to produce and star in Lee's next mooted project, Jesus Henry Christ, about a boy created in a petri dish and raised by a left-wing feminist.

There is evidence that older actresses can still land plum parts. Michelle Pfeiffer gives a nuanced performance as an ageing but still beautiful courtesan in Stephen Frears' forthcoming Chéri. Kim Basinger excels as the married woman having an affair in Guillermo Arriaga's The Burning Plain.

Meanwhile, Roberts can look to the unlikely example of Clint Eastwood. The grizzled old master has been enjoying strangely mixed fortunes of late. His impressive 1920s Los Angeles-set Changeling did only middling business despite the presence of Angelina Jolie as the mother desperate to reclaim her kidnapped child. However, as if to prove that ageing stars still can open movies, Eastwood has been doing roaring business with Gran Torino. Variety this week reported that the film, in which Eastwood stars as a curmudgeonly OAP version of his old vigilante self familiar from Dirty Harry days, is speeding "its way to become his top-grossing film of all time at the international box-office".

Eastwood is in his late seventies. Roberts is only in her early forties. It's a sign of the sexism of the industry that her age already seems to be such an issue when it comes to assessing her ability to "open" a movie. Whatever the fate of Duplicity, though, there is no sign that her career has quite run out of steam yet.

'Duplicity' is out on 20 March

BOX-OFFICE BELLES

Kate Winslet
Now that she at last has her Oscar, Winslet is even more in demand than before, especially when producers are trying to find stars to tackle the heavyweight roles that might have gone Meryl Streep's way a generation ago. When it comes to opening a movie, awards nominations always help and Winslet invariably seems to get them.

Reese Witherspoon
Voted the most "likeable female celebrity" of 2007, Witherspoon is also one of the most bankable stars of her generation. Like Julia Roberts, she has her own production company. Like Roberts, she has been able to mix and match between frothy comedies (for example, the 'Legally Blonde' films), off-beat fare ('Election') and more earnest drama ('Rendition'). She won plenty of awards for playing June Carter opposite Joaquin Phoenix's Johnny Cash in 'Walk the Line'. It was confirmed this month that she will be reunited with 'Election' director Alexander Payne on 'Downsizing', Payne's film about miniature people which will also star Paul Giamatti and Sacha Baron Cohen.

Anne Hathaway
With 'Brokeback Mountain', 'The Devil Wears Prada' and 'Rachel Getting Married', Hathaway has shown that she can excel in darker dramatic roles as well as in the lighter vehicles ('The Princess Diaries') that first made her name. The recent 'Bride Wars' wasn't her finest hour but at least it showed she hadn't lost her populist credentials.

Emily Blunt

Emily Blunt managed the delicate task of transforming Britain's most dowdy monarch Queen Victoria into a passionate, headstrong coquette in 'The Young Victoria'. In a short career, she has already racked up an impressively diverse list of credits and looks poised for a major breakthrough.

Eva Green
"So beautiful, it's indecent," Bernardo Bertolucci said of the French actress who played Vesper Lynd in 'Casino Royale'. It's a moot point whether she can "open" a movie on her own but she seems able to move at ease between blockbusters like the Bond movie and 'The Golden Compass' and more esoteric arthouse offerings.