Olivia Colman wins best actress Oscar for 'The Favourite'

Britain's Olivia Colman won a surprise best actress Oscar on Sunday for her clever performance as an ailing, petulant monarch in historical film "The Favourite", delighting the audience with a tearful and humorous acceptance speech.

It was the first Academy Award and first nomination for Colman, 45, who is one of the most beloved and prolific actresses in British television. Colman also won the Golden Globe and British BAFTA awards for her performance.

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"It's genuinely quite stressful. This is hilarious," Colman said in accepting the trophy, which she won over nominees Glenn Close, Lady Gaga, Melissa McCarthy and Yalitza Aparicio.

"And my kids who are home watching - well if you're not, kind of well done," Colman said. "I sort of hope you are. This is not going to happen again."

"The Favourite" sees Colman portray Britain's 18th-century Queen Anne as an insecure, frail and tempestuous royal who treats her horde of rabbits as if they were her dead children and has secret love affairs with characters played by Emma Stone and Rachel Weisz.

Stone, sitting near Colman in the Dolby Theatre, also broke into tears as the award was announced, could be seen repeating "oh my God" over and over again.

Colman, who keeps a low profile in Hollywood but is regarded as a national treasure in Britain, has said that in Queen Anne she enjoyed playing a woman who is "filthy and sexy and emotional and sad" rather than attempting to be "gorgeous all the time and a little bit sort of prettily flawed."

The self-effacing actress began her career in England some 20 years ago, racking up credits on comedy sketch shows and in dramatic roles such as television police murder mystery "Broadchurch" and spy thriller "The Night Manager."

She will next play the role of a middle-aged Queen Elizabeth in the upcoming third season of the Netflix drama "The Crown" about the British royal family.