Nancy, the unsung star of 'The Simpsons', tells of her life as a 10-year-old boy

Nancy Cartwright, having appeared in such hit shows as Cheers and Fame , might have preferred to be remembered as an on-screen actress. But she will go down in history as the impersonator of a 10-year-old boy with yellow hair.

Most of the millions of viewers who tune in to the world's most successful prime-time cartoon series have no idea that the voice of Bart Simpson is really that of a 47-year-old mother of two children.

But Ms Cartwright is planning to temporarily break away from Springfield, the home of The Simpsons , to launch her one-woman show at the Edinburgh Festival Fringe in the summer.

The actress has voiced Bart for the past 17 years and her stage show is called My Life as a 10-year-old Boy . The project will also raise the profile of the artists who provide the voices for The Simpsons , who have become just as important to the globally popular cartoon series as the animators and the scriptwriters. Without Dan Castellaneta, who provides the voice of Homer Simpson and gave the world the expression "Doh!", the show would struggle to come out at all.

Mr Castellaneta does a range of voices for other Springfield residents, including Krusty and Grampa Simpson, and often finds himself having three-way conversations with his other characters. Harry Shearer started his career with a part in the classic film Abbott and Costello Go To Mars before creating the spoof rock documentary This is Spinal Tap , in which he played the heavy-metal bass guitarist Derek Smalls.

To fans of The Simpsons , he is the voice of Mr Burns and Smithers, and numerous other unlikely characters introduced by the scriptwriters. The importance to the show of the "voice cast" came to a head in 1998 when the actors became locked in a contract dispute with Twentieth Century Fox Television, which makes The Simpsons .

Mr Shearer, at the conclusion of the dispute, complained to Variety magazine: "I find it ironic that a cast deemed instantly replaceable weeks ago is now indispensable."

The Simpsons , which is in its 15th series, is shown in 60 countries.

Ms Cartwright learnt some of her skills by studying with Daws Butler, the voice of such cartoon characters as Yogi Bear and Huckleberry Hound.

Ms Cartwright and Mr Castellaneta appeared at the Edinburgh Festival Fringe in 2000 in what became the fastest-selling show staged at the festival.

Mary Shields, the associate director of the Assembly Rooms, Edinburgh - the venue for the festival - said Ms Cartwright's show would be more personal and would be partly based on her best-selling book, also called My Life as a 10-year-old Boy .