Dame Helen Mirren was named best actress for her role in The Queen at the Academy Awards in Los Angeles on a night that saw Martin Scorsese's crime drama The Departed pick up four awards.

Mirren was an overwhelming favourite to land the Best Actress accolade with some bookmakers having paid out on her winning last week.

She plays Elizabeth II in the British film, directed by Stephen Frears, about the Royal Family's reaction to the death in 1997 of Princess Diana.

Accepting her award, Mirren said: 'For 50 years and more, Elizabeth Windsor has maintained her dignity, her sense of duty and her hairstyle. If it wasn't for her, I most certainly wouldn't be here - ladies and gentlemen, I give you the Queen.'

Her Oscar marked the culmination of a hugely successful awards season that has seen her win a Bafta, Golden Globe and Screen Actors Guild prize, among others.

Forest Whitaker, a similarly hot favourite to win, duly picked up the Best Actor award for his portrayal of Ugandan dictator Idi Amin in The Last King of Scotland.

Elsewhere, Scorsese's The Departed won in the Best Picture, Best Adapted Screenplay and Best Film Editing categories, while Scorsese was named Best Director.

Best Supporting Actor went to Alan Arkin for his role in Little Miss Sunshine, which also won Best Original Screenplay.

Pan's Labyrinth was also a big winner, picking up the Best Cinematography, Best Art Direction and Best Make-Up awards, while An Inconvenient Truth and Dreamgirls went home with two Oscars each.

Jennifer Hudson was named best supporting actress for Dreamgirls, her first major film role.

Best Animated Feature went to Happy Feet, while German production Das Leben der Anderen (The Lives of Others) was the Best Foreign Language Film.