Prince William and Kate Middleton had a very royal date night this evening (5 December) as the couple were guests of honour at this year's Royal Film performance, the UK premiere of Mandela: Long Walk To Freedom.

And true to form, the Duchess outshone the A-List movie stars in attendance, as she brought her own brand of royal glamour to the red carpet at the Odeon Leicester Square.

Kate defied the extreme weather warnings to bare some leg in an Angelina Jolie inspired white, floor-skimming evening gown by French designer Roland Mouret, which was slashed to the thigh.

With her hair swept up in a modern pony tail to showcase an eye-catching piece of costume jewellery, the Princess looked stunning on the arm of her husband William, who was dressed in traditional black tie.

Before the screening the Duke and Duchess met with the cast and crew of the movie, including British actor Idris Elba, who portrays South Africa's legendary first black President in the film and 28 Days Later star Naomie Harris, who plays his wife Winnie.

Speaking at the premiere Harris said she was thrilled to meet William and Kate. 'I have met him before several times at the polo and I hear she is just as down to earth as him,' she said.

The Duke and Duchess also had an opportunity to talk with Mandela's daughter Zindzi Mandela who helped the filmmakers create an intimate portrait of the iconic leader.

Zinzdi revealed that her father, who is currently in a critical condition at his home in Johannesburg, has seen some clips of the film. While the movie has received mixed reviews, she said she was happy with the final film. "I love it. I think it's authentic," she said.

Based on the former ANC leader's autobiography, the film directed by Justin Chadwick chronicles Nelson Mandela's life from his childhood in a rural village through to his inauguration as the first democratically elected president of South Africa.

While proceeds from the night will go to the Cinema and Television Benevolent Fund, which supports industry employees in times of hardship, this year's film will also raise money for the Nelson Mandela Children's Fund.