Amanda Seyfried works the red carpet at UK premiere of new film In Time

It's an evening wear option that has been seen on many a celebrity this year as it combines smart and sexy to perfection.

Especially those with enviably long legs, such as Amanda Seyfried, who showed off her terrific set of pins in an electric blue shorts suit in London tonight.

The actress stood out on the red carpet in the shiny suit as she arrived for the UK premiere of her new film In Time.

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Electric blue beauty: Amanda Seyfried showed off her long toned legs in a sexy shiny shorts suit as she arrived at the UK premiere of her new film In Time

And on this unseasonably balmy Halloween night, it proved to be the perfect outfit as she posed for pictures on the carpet looking very sexy and chic but respectable and smart at the same time.

And the actress proved that she didn't need to spend thousands on her wardrobe either as she revealed that her suit came from high street chain H&M.

Amanda, 25, was joined at the Curzon Mayfair cinema by her co-star Justin Timberlake.

Adding some length: Amanda teamed her shiny suit with towering black heels that made her legs go on forever

And he certainly does know how to bring sexy back as he arrived looking very dapper and handsome in a black suit, which, at some glances, looked like it was made out of leather.

The pair posed for the cameras as they arrived at the screening of the film, which is released in the UK this week.

The film, by The Truman Show director Andrew Niccol, is a sci-fi thriller set in the future where people stop aging at 25 years old, but are engineered to live for just one more year after that.

Co-stars: Amanda was joined at the premiere by Justin Timberlake, who pays the lead role in the sci-fi thriller

What's so funny? Justin and Amanda share a private joke as they head down the red carpet

Time is money, quite literally, as it is used as a unit of currency and people can buy time to make them live longer, which doesn't bode well for the lower and poorer classes, many of whom die at 25 while the rich live on for hundreds of years.

Timberlake plays poor Will Salas who is falsely accused of murder and stealing time from the victim, and must figure out a way, with the help of hostage Sylvia Weis, played by Amanda, to bring down the system and make it through another day of his life.

The film also stars Olivia Wilde, Cillian Murphy, who was also at the premiere, Alex Pettyfer and Vincent Kartheiser, best known for his role as Pete Campbell on Mad Men.

Pin-up: Amanda signs posters and photos for her adoring male fans

Who do I make this out to? An obliging Justin topped to talk to fans and sign some autographs

Speaking to the press outside the screening, Timberlake revealed that he needed special running training for his role and joked he had never done so much running in his life.

But he said he didn't mind putting in the extra hours of hard work as he really enjoyed playing the character.

He said: 'This is the first character I have played that I really admire a lot. He is brave and I hope I would come out swinging too.'

Co-stars: Justin and Amanda posed with Cillian Murphy, who plays a policeman on the hunt for Justin's character

He added: 'I think it's an intriguing concept for a movie. I don't know if it would work in real life but I think the best sci-fi films have a way of taking other-worldly concepts and throw some metaphors at us.'

Seyfried sang her co-star's praises as she said he helped her when she found herself sprinting in stilettos.

She said: 'He saved my life while I was running in six-inch YSL heels.'