She is such a hot favourite to land the Best Actress award on Sunday for her starring role in The Queen that bookmakers have already closed the betting.

But Dame Helen, 61, fears her winning streak - more than 20 prizes including a Bafta and a Golden Globe - may count against her.

"I don’t feel greedy exactly, but I worry people must be getting fed up with me," she told The Daily Telegraph.

"I’m nervous about the Oscars. I mean, I’m calm in myself. But I feel nervous because I’m representing myself, the film, my country - and my monarch. It’s a lot. I just hope I don’t make a fool of myself."

But she insisted: "I’m not weary of awards yet. I’m happy to see this through."

The Queen’s director, Stephen Frears, described Dame Helen’s casting as the monarch as "sort of the best piece of casting there’s ever been in the world". He is a nominee for Best Director.

But he does not rate his chances against the competition, which includes Clint Eastwood for Letters From Iwo Jima and Martin Scorsese for The Departed.

"Against Marty or Clint Eastwood? I don’t take that as a serious possibility. So I’ll have a nice time. I’ll worry more about the other people," he said.

Bookie pays out on Mirren Oscar win - Feb 21 2007
William Hill has closed the book on Dame Helen Mirren winning a best actress Oscar this Sunday.

The bookmaker is paying out over £50,000 to punters who have backed her.

The actress is 66/1 on to win for her performance in The Queen.

Meryl Streep is the 12/1 second favourite for The Devil Wears Prada.

It is the first time in over 20 years of Oscar betting that William Hill has made such a move.

"Should the unimaginable occur and Dame Helen fails to win the Oscar, then she will have been robbed and so will we," said spokesman Rupert Adams.

He explained: "We have not taken this decision lightly, but it has been one-way traffic since we opened the betting with almost every penny accepted on the best actress market for Dame Helen.

"It has got to the stage where we just don’t want to take any more.

"Dame Helen has swept the board at all the major awards and looks a certainty to walk away with the Oscar.

"Hopefully the decision to pay out will persuade punters to reinvest some of their winnings on the other categories, which are far more competitive."

Forest Whitaker is 5/1 on to win the best actor Oscar for The Last King of Scotland, with British hopeful Peter O’Toole second favourite at 10/3.

Dame Helen wins Bafta - Feb 11 2007
Dame Helen Mirren was crowned queen of the Baftas, when she won best actress for her role as the monarch.

The 61-year-old had been favourite to land the prestigious gong following a string of awards for her acclaimed performance in The Queen.

Dame Helen had faced fierce competition for best actress from Dame Judi Dench, 72, for her role as a lonely but twisted history teacher in Notes on a Scandal.

She also beat Meryl Streep, Penelope Cruz, and Kate Winslet to the best actress title.

Dame Helen picked up her award, saying: "This is great.

"What an honour, especially to be nominated - just to be nominated - amongst those incredible powerhouse performances this year from women.

"I applaud them. I think they were absolutely fantastic. Write more roles for us like that please. Thank you Peter (Morgan), keep writing."

She also paid tribute to her co-star, saying: "Michael (Sheen) was fantastic as Blair".