Princess Diana shocked dance instructor and confidante Anne Allen with what she said after performing a spicy dance for then-husband King Charles at a 1985 charity event.

In the new book Dancing With Diana: A Memoir, Allen recounts the telling way the princess reacted once she wrapped a routine designed to surprise the future king, who seemed to be left less than impressed.

Allen, who grew close to Diana during hundreds of secret one-hour ballet lessons they shared from 1981 to 1989, hinted that the Princess of Wales was let down by Charles response, leading her to allude to unhappiness in her notoriously tumultuous marriage.

She just wanted him to be thrilled, Allan told People magazine in an interview released Thursday. When you feel that somebody doesnt love you, that has an effect on you. She kept thinking that there was love there and that there would be love there. And Im sure there was.

During a charity ball at the Royal Opera House in London in December 1985, Princess Diana teamed up with acclaimed British dancer Wayne Sleep for a piece of choreography set to the Billy Joel classic Uptown Girl.

Allen said the British royal was captivating as she strutted across the floor with Sleep for the jazz routine, especially during the climax of the dance.