Julia Roberts is the prettiest woman in town as she pulls on a thigh-skimming minidress and dazzling silver heels for the UK launch of new movie Leave The World Behind

Julia Roberts was every inch the Pretty Woman on Wednesday evening as she celebrated the UK launch of new film Leave The World Behind in London. 

On a freezing night in London, the Oscar-winning actress, 56, warmed up proceedings in a thigh-skimming miniskirt and dazzling silver embellished heels while greeting fans outside Curzon Mayfair. 

A powder pink double-breasted blazer completed the look, while a diamond encrusted necklace complimented her distinctive footwear as she made her way inside the venue.    

Roberts was joined by co-star Myha'la Herrold and director Sam Esmail at Curzon Mayfair ahead of the psychological thriller's official UK release on  December 8. 

But the actress, who also co-produces her latest film, was without fellow stars Kevin Bacon, Ethan Hawke and Mahershala Ali. 

Roberts says her new film is a multilayered disaster thriller that allowed her to play someone very different from herself.

Executive produced by former U.S. President Barack Obama and Michelle Obama, the movie is written and directed by Mr. Robot creator Esmail and based on the best-selling novel of the same name by Rumaan Alam.

It sees Roberts' character Amanda, her husband and two children head on an impromptu holiday in a small Long Island town. 

Their getaway is interrupted when a man and his daughter, played by Mahershala Ali and Myha'la Herrold, turn up on their doorstep claiming to be the owners of the upmarket residence and requesting to stay the night. 

As tension builds between the two families, strange events start occurring around them and they find themselves under the same roof trying to make sense of the chaos outside.

'There's always about 17 and a half things going on at one time in every scene for each person. It was just all the layers of the people and the circumstances,' Roberts told Reuters at the film's premiere in London on Wednesday.

The Hollywood star cherished the challenge of playing cynical advertising director Amanda.

'Just the idea of playing someone who's sort of intrinsically suspicious and a little prickly, which is not my nature, but to still make her human and approachable and likeable.' 

Fans of Alam's book should not expect a faithful adaptation, Esmail warned.

'Something that works in a literary medium may not work in a cinematic medium. I was very upfront with Rumaan that I really was going to take liberties with the interpretation. 

'I ran through all the ideas, he was on board and then in a lot of ways I think we both got what we wanted because his book and the film are kind of two different standalone pieces that kind of operate independent of one another.' 

The actress was celebrating the launch of her new film after sharing a rare photo of herself with her twins Hazel and Phinneas.

She uploaded a black-and-white childhood throwback with her little bundles of joy in order to mark their 19th birthday this Tuesday.

Both twins were safely nestled in their mother's arms as they sat on her lap.

'There are no words for the joy, the fun, the wild rumpus of life together,' the proud mother wrote heartwarmingly in her caption.

The Pretty Woman star shares her twins and her 16-year-old Henry with her second husband, cinematographer Daniel Moder.

Julia and Daniel celebrated their 20th wedding anniversary last year on the Fourth Of July, having tied the knot at her New Mexico ranch on Independence Day 2002.

In an interview a few of months after their milestone anniversary, Julia served up a hint at why their marriage has proven such a keeper.

'I always say that same thing and I'm sticking with it,' the Hollywood superstar explained to E! News. 'It's making out. Lots of making out.'

She was giving the interview alongside her Ticket To Paradise co-star George Clooney, who joked: 'I make out with Danny, too.'

During the same promotional tour, Julia and George appeared on the Today show where she offered her reflections on motherhood.

Julia laid out her theory that children 'have chosen us in this moment to be their stewards and their shepherds in this life experience.'

She met her husband 'when I was ready,' whereupon 'you call these children into your lives when we're ready to best partner with them.'

The Eat Pray Love star confessed: 'Sometimes I get gripped with fear of blowing it, and sometimes I've just said to my kids, like: "So, today me as a mom, can we just - can we just take that off the boards? Because I blew it."'