London Film Festival is branching out of the city and into the suburbs this Sunday for a special celebration to mark its 50th anniversary.

A host of cinemas across south west London have been chosen to take part in a unique event called 50 Screens.

For just £5, adventurous cinema goers will get the chance to see a great feature - the only catch' is that the films on show are a surprise.

"For years we have done this on the second Sunday of the festival at the Odeon West End and every year the tickets have sold out faster than for any other event," said Sandra Hebron, artistic director of London Film Festival.

"I don't know what it is about the screenings - people just like a surprise, I guess."

As long as you have an open mind, the surprise is normally a pleasant one.

"Obviously, the whole appeal of the event is that the films are secret so I can't give away any clues," added Sandra.

"Only myself and the projectionists know what the films are. What I can say is that the films on show won't be strange little shorts that no-one has ever heard of.

"In most cases they will be preview screenings - big films with big stars that haven't yet gone on general release."

Unlike in previous years, when there has only been one surprise screening, this year there will be an added Russian Roulette element to the event. Each different venue will preview a different film, meaning that the cinema you choose could be important.

"We are doing a few special screenings at unusual venues, like Heathrow Airport, Holloway Prison and St Thomas's Hospital, where we have chosen films to match the surroundings", said Sandra.

"The arthouse cinemas might show a new arthouse film, while the multiplexes will show more mainstream features."

An added bonus will be a special presentation before each screening from either someone involved in the making of the film, a personality involved in the festival or a local celebrity.

"I can't think of anywhere else that 50 preview screenings have taken place simultaneously, so I am sure it will be a record-breaking event.

"It is certainly a fitting way to celebrate our anniversary."

Last Wednesday's opening ceremony was a testament to the level of esteem the London Film Festival is now held in across the world.

The Last King of Scotland - the first feature film from Touching the Void director Kevin Macdonald - opened the festival with a special gala premier screening.

The stars of the film turned up for the red carpet treatment, including Forrest Whittaker, Gillian Anderson and James McAvoy. "It was a fine start to what I'm sure is going to be the best festival yet," said Sandra.

"I know the British film industry takes a battering in the press, but I don't think there is any doubt that this country is a hotbed of world cinema. The problem is finding enough money to fund the industry, but the talent is here and that is why the London Film Festival has become such an important showcase."