Wayne Sleep says his friend Princess Diana had a "schoolboy" sense of humour.
The 72-year-old choreographer was the late princess' dance teacher, and he admits that her "charismatic" nature came through in her routines.
He shared: "We had the same schoolboy humour. I was her sort-of jester, in a way, but we did get on incredibly well. We had something that clicked.
"She had natural style. She could do the high kick, she could do a pirouette and she had lovely swinging hips.
"She had that thing called charisma. She was charismatic and even when she spoke with that very quiet voice, it was something that pulled you in and you just wanted to embrace her all the time."
Diana - who died in a car accident in September 1997, aged 36 - once joined Wayne to perform a routine to the Billy Joel song 'Uptown Girl' at the Royal Opera House in London during the Friends of Covent Garden show in 1985.
The choreographer can still remember the audience being wowed by her surprise appearance.
He told HELLO! magazine: "They gasped; they were frozen. It took a while for them to actually believe it was her."
The pair's dance at the Royal Opera House was practiced in secret so it could be performed as a surprise for Diana's husband Prince Charles, but Sleep had major reservations about whether they would be able to pull it off due to the height difference between the pair as he is 5ft 2in, whilst Diana stood at 5ft 10in.
Previously recalling the moment when Diana approached him with the idea, Sleep wrote in The Daily Telegraph newspaper: "I said to Princess Diana – this will never work, Ma’am. You’re so much taller than me."
The dance was recreated in Netflix royal drama series 'The Crown' with Sleep, Diana and Charles played by Jay Webb, Emma Corrin and Josh O'Connor respectively.