Nicole Kidman holds onto  plunging dress to prevent wardrobe malfunction while joking with co-stars at Before I Go To Sleep premiere

By Bella Brennan for MailOnline

They might have been attending the premiere of a thriller film.

But Nicole Kidman, Anne-Marie Duff and Colin Firth couldn’t have been further from scary as they joked about on the red carpet for the UK gala screening of Before I Go To Sleep at the Ham Yard Hotel in Soho, London, on Thursday evening.

However the fun and games almost entered dangerous territory with Nicole having to keep a close guard on her plunging frock, and at times the actress had to hold the opening around her chest together to prevent an unwanted wardrobe malfunction.

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Elegant... Nicole Kidman stunned when she attended the UK premiere of her latest film Before I Go To Sleep at Ham Yard Hotel in Soho, London on Thursday evening

Elegant... Nicole Kidman stunned when she attended the UK premiere of her latest film Before I Go To Sleep at Ham Yard Hotel in Soho, London on Thursday evening

Holding on tight: The 47-year-old kept a close watch on her plunging frock to prevent an unwanted wardrobe malfunction 

Holding on tight: The 47-year-old kept a close watch on her plunging frock to prevent an unwanted wardrobe malfunction 

The Australian actress, 47, looked elegant in a long-sleeved gown with colourful butterflies adorned throughout it.

The mother-of-four opted for metallic peep-toe heels and a delicate beaded necklace and silver earrings while her auburn locks were swept into a low pony-tail and teamed with a side-parting. 

Co-star Anne-Marie Duff, 43, worked a camel-coloured leather dress with a lilac bodice and closed-toe shoes.

Great mates! Nicole and her co-stars Anne Marie Duffy (middle) and Colin Firth have clearly become good pals after filming the thriller together

Great mates! Nicole and her co-stars Anne Marie Duffy (middle) and Colin Firth have clearly become good pals after filming the thriller together

A stylish trio... Anne-Marie  worked a camel-coloured leather dress with a lilac bodice and closed-toe heels

A stylish trio... Anne-Marie worked a camel-coloured leather dress with a lilac bodice and closed-toe heels

Always a pleasure: 'For me, I get to play opposite one of the greatest actors in the world, so I'm always like, "Offer Colin everything." I just love working with him,' Nicole explained of Colin 

Always a pleasure: 'For me, I get to play opposite one of the greatest actors in the world, so I'm always like, "Offer Colin everything." I just love working with him,' Nicole explained of Colin 

Busy! Anne-Marie, who is married to James McAvoy, has also wrapped filming  Suffragette and Molly Moon: The Incredible Hypnotist this year

Busy! Anne-Marie, who is married to James McAvoy, has also wrapped filming Suffragette and Molly Moon: The Incredible Hypnotist this year

Glowing... The 43-year-old sported natural looking make-up and wore her hair slicked back 

Glowing... The 43-year-old sported natural looking make-up and wore her hair slicked back 

Meanwhile 53-year-old Colin Firth, who was crowned GQ’s Leading Man Of The Year on Tuesday evening, opted for a timeless dark grey suit and a crisp white shirt. 

The mystery thriller follows amnesiac Christine Lucas (Nicole Kidman), who loses her memory every night.

It emerges that she has been using the camera to record a video diary, detailing her life to help her remember.

Recording herself, she says: 'My name is Christine Lucas. As I sleep my mind will erase everything that I know – everything that I did… I have to remember.'

In a flutter! The Australian actress kept a firm grasp on her chic butterfly dress
Dazzling: Nicole added a stunning drop necklace to finish off her look

In a flutter! The Australian actress kept a firm grasp on her chic butterfly dress

Stand out stars! Colin Firth opted for a timeless dark grey suit and a crisp white shirt

Stand out stars! Colin Firth opted for a timeless dark grey suit and a crisp white shirt

United once more: Colin and Nicole worked together in the 2013 film The Railway Man 

United once more: Colin and Nicole worked together in the 2013 film The Railway Man 

Memory blank... The mystery thriller follows amnesiac Christine Lucas (Nicole Kidman), who loses her memory every night

Memory blank... The mystery thriller follows amnesiac Christine Lucas (Nicole Kidman), who loses her memory every night

Haunting: In the film Christine begins to keep a video diary in a bid to connect the dots as to what has happened 

Haunting: In the film Christine begins to keep a video diary in a bid to connect the dots as to what has happened 

Timeless style: Nicole swept her auburn locks into an elegant low ponytail   

Timeless style: Nicole swept her auburn locks into an elegant low ponytail   

Before long Christine learns that she was brutally attacked, the reason for her massive memory loss, and she must decide who to trust as she is told different stories.

'He says he's protecting you but don't trust him,' she adds, but is she referring to her doctor, or to her husband? 

Speaking to the BBC about the role, Nicole said: ‘I liked the claustrophobia of it. How do you play someone trying to piece their life together every single day?'

Happier than ever! In 2006 the actress married her Shameless co-star James McAvoy and they welcomed their first son Brendan in 2010 

Happier than ever! In 2006 the actress married her Shameless co-star James McAvoy and they welcomed their first son Brendan in 2010

Adding: 'The video diary was very compelling, I thought, as a tool in the construction of the movie. And there’s not a lot of female-driven thrillers.’

‘I like doing them [thrillers]. I think I like the pace and you really have to access true emotions and you have to make it very, very real even though the circumstances are very extreme. I like psychological thrillers.’

Before I Go To Sleep hits cinemas on September 5. 

A compelling script: 'I liked the claustrophobia of it. How do you play someone trying to piece their life together every single day?,' Nicole said of the film

A compelling script: 'I liked the claustrophobia of it. How do you play someone trying to piece their life together every single day?,' Nicole said of the film

Having a blast: The actors didn't take themselves too seriously on the red carpet 

Having a blast: The actors didn't take themselves too seriously on the red carpet 

Big week... On Tuesday evening the 53-year-old was crowned GQ's Leading Man Of The Year

Big week... On Tuesday evening the 53-year-old was crowned GQ's Leading Man Of The Year

All together now! (L to R) Nicole Kidman, Colin Firth, Anne-Marie Duff, S. J. Watson and Rowan Joffe pose for a photo

All together now! (L to R) Nicole Kidman, Colin Firth, Anne-Marie Duff, S. J. Watson and Rowan Joffe pose for a photo

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