SHE would become the greatest dancer of her age, honoured as prima ballerina assoluta by the Royal Ballet when she finally retired in her 60th year. But in January 1940, aged just 20, Margot Fonteyn was struggling to keep her confidence as she danced for a country at war.
"Each performance which is not as good as I can possibly do is a waste of time," she wrote to the artist who had fallen in love with her. "Sometimes I am too exhausted to do very well, but more often it is simply a kind of apathy which is deadly."
Nine handwritten letters from Fonteyn to Captain Robert Furse, a painter whom she met in Paris in 1936, go on show this month at the Churchill Museum and Cabinet War Rooms in London. Bought by the Royal Opera House, they have never been seen before.
The dancer's relationship with Captain Furse, of the Rifle Brigade, did not last. Dancing might not fulfil her life, she wrote, but "I don't imagine that it will ever come second to my love for a person".
The letters show her falling instead for the charismatic music director of the Sadlers Wells Ballet, Constant Lambert. She hoped to marry the heavy-drinking, talented composer, but his own attentions soon wandered elsewhere.
They give a remarkable insight into the war years, when Fonteyn toured Britain and Europe in a series of performances that would leave her emotionally and physically exhausted, but turn her into a national heroine.
Sadlers Wells, the future Royal Ballet company, faced breaking up as the war began, but Lambert and the choreographer Frederick Ashton persuaded the government it could help to boost morale. The dancers toured army bases and British cities under the bombs, including Glasgow.
"It was an amazing time to have lived. You knew what you were doing was a very valuable war aid," Fonteyn wrote.
In 1940, Fonteyn and the company were sent to Holland on a goodwill tour. The Germans invaded and they narrowly escaped across the Channel. They survived bombings in Bath, and lesser troubles like boils, which she complains of in one letter.
Christina Franchi, exhibitions manager for the Royal Opera House collections, said: "The letters were written during the war years, when the company toured continuously.
"She is surrounded by people she perceived as great artists. She is much younger than them. She obviously has self-doubt.
"What the letters reveal is just how exhausted she was the whole time, because she was dancing all the time. There was a time in London when they would do three shows a day."
The Sadlers Wells became Britain's national ballet company, and Fonteyn was established as its star. In 1946, she danced in Sleeping Beauty, reopening the Royal Opera House in London. In 1949, she went to New York and won a rapturous welcome on her US tour, helped by the American troops who had seen her during the war.
Born Margaret Hookham to an English father, borrowing a surname from her Brazilian roots, Fonteyn danced until 1979, partly to pay medical bills for her quadriplegic Panamanian husband, Tito Arias. She died in Panama in 1991.
In the letters, she often speaks of being dissatisfied with her own dancing.
"A lot of artists are their own worst critics. We go and see the performance and we enjoy it, but for them it is something else. A lot of dancers in their careers will say they only achieved what they wanted in half a dozen performances," said Ms Franchi.
"They are aiming for perfection, in terms of characterisation and music and everything else. The fact that she felt she wasn't giving a performance didn't mean she wasn't giving a wonderful performance."