Princess Di admitted she was 'ashamed' of her bulimia

Princess Diana was "ashamed" of her bulimia, her long-time dance teacher says in a new memoir.

The British royal, who was died aged 36 in a 1997 Paris car crash, was stricken with the eating disorder before she got married to Prince Charles, and continued to suffer from it as their marriage collapsed.

Anne Allan said Diana asked to cancel her dance lessons before revealing she had bulimia in her autobiography Dancing with Diana.

Allan said Diana's lady-in-waiting Anne Beckwith-Smith called to say the princess may want to stop her lessons, but when she asked Diana the royal said she was "annoyed" at the move and made it clear the Palace wanted her to end the lessons and not her.

Soon afterwards, the teacher said Diana declared she was "ashamed" to admit she was suffering from bulimia.

But Allan said about how she feared the royal was suffering from the disorder after Diana fainted during a trip to Vancouver in 1987: "I gathered that the Palace had concerns and were aware, or at least suspected the problem.

"I realised that they may have been worried that it could be dangerous if anyone from the outside world found out… the more I thought, the angrier I felt.

"If the 'establishment' knew definitively, had anyone reached out to offer help and guidance? It didn't seem that they had.

"Had they dismissed this disease as a sign of weakness, not understanding the mental anguish Diana was in?"

Allan added she was left "angry" at future king Charles' affair with his now-wife Camilla at the time of Diana's bulimia battle.

"Did Charles think that this was acceptable behaviour, and that Diana should just turn her back and ignore what was going on? Was he relieved that his wife was in her own extramarital affair?

"Did it affect him at all? It didn't seem so."

* Dancing With Diana: A Memoir will be released in the US on September 10.