Diaz 'is ideal Sound of Music actress'

She also admitted that the star of My Fair Lady told her she should have played Eliza Doolittle.

“Audrey Hepburn told me: ’You should have done it but I didn’t have the guts to turn it down,’ but she was a great friend and a lovely, dear lady.”

Asked why The Sound of Music was still a family favourite she replied: “It’s about decency. It’s about love of family and love of country. It had the amazing scenery but phenomenal music and it’s something the whole family can enjoy.”

She added she didn’t feel her role in the film or the part as Mary Poppins was a burden.

“I am the lucky person that got asked to play those movies. There are hundreds of other ladies who sing just as well or better than I do and I was the lucky one who got asked,” she said.

The famous opening scene of the 1965 film sees Dame Julie happily running through the mountains as she sings. But the star said the making of that scene wasn’t quite as serene as it appeared.

“I will never forget it, there was a large helicopter coming towards me through the mountains with a brave cameraman hanging out the side.

“We shot the scene many times and at the end of each take the helicopter would circle round. The downdraft nailed me flat onto the grass and a couple of times I bit the dust. At first it was funny but after several times I began to get very angry.”

The star gave up musical roles for health reasons and has recently provided the voice of Queen Lillian in the forthcoming Shrek 3.

“I miss singing very, very much but the best thing is I have never been busier.”

She added she was halfway through writing her autobiography but it was proving rather difficult.

“It’s hard to find one’s own voice when you write, it’s easier to write a child’s book with a voice that you create.

“I so want to do it well and do justice to all the wonderful people I’ve worked with.”