Good Night, And Good Luck is Clooney's second film as director

Good Night, And Good Luck - Clooney's second film as a director - is set during the early days of broadcast journalism in 1950s America.

Clooney attended the screening in London's Leicester Square.

More than 180 films from 50 countries were shown at this year's festival, which began on 19 October.

'Directing more enjoyable'

Hollywood star Clooney signed autographs for dozens of fans outside the cinema.

He said he found directing more enjoyable than acting.

"You can last a little longer," he said. "You can get old and grey and they still let you do the job."

Clooney met fans before the London screening

Clooney said his back, which he injured in an on-set accident during the making of another film, was "pretty good".

"If you drink enough it doesn't hurt so much," he joked.

He was non-committal when asked whether he would be hosting the wedding of film stars Brad Pitt and Angelina Jolie, as widely reported.

"Everybody keeps asking me that," Clooney said. "I don't know."

The annual film festival opened with John Le Carre's thriller The Constant Gardener, starring Ralph Fiennes and Rachel Weisz.

Joaquin Phoenix plays the late Johnny Cash in Walk the Line

Both films were contenders for the Golden Lion at the recent Venice Film Festival, alongside Takeshi Kitano's Takeshis', Philippe Garrel's Les Amants Reguliers and Tery Gilliam's The Brothers Grimm - all shown in London.

Cameron Crowe's Elizabethtown, Steven Soderbergh's Bubble, Lars Von Trier's Manderlay and the directorial debut from Gosford Park screenwriter Julian Fellowes, Separate Lies, all had their UK premieres during the festival.

Gala screenings included James Mangold's Johnny Cash biopic Walk the Line and hit French documentary The March of the Penguins.

On Thursday British producer Gayle Griffiths was awarded the festival's �15,000 UK Film Talent Award.