Sir Elton John claims he once jived with the Queen to rock'n'roll hit Rock Around The Clock.
The musician said she asked if she could join him on the dancefloor when he attended an event at Windsor Castle.
Sir Elton talks about his dance to the Bill Haley tune as he recalls his royal encounters when he appears as a guest on tomorrow night's Graham Norton Show on BBC1.
He explained: "Princess Margaret and I became friends. I took her to the cinema once at the Odeon Kensington. We had a lovely time and then we went out to dinner and I took her home. Nothing happened of course.
"I also once danced with Princess Anne at Prince Andrew's 21st Birthday and the Queen came over and said, 'may I join you?'. We danced to Bill Haley's Rock Around the Clock. It was one of the most surreal moments of my life.
"Having been born in a council house in Pinner the chances of dancing with the Queen at Windsor Castle were pretty long."
He also told how enjoys his children's bathtimes before he goes onstage during tours - sometimes still with foam on his outfits.
The 66-year-old performer - who has two children with his partner David Furnish - said: "Everywhere I go they come with me. I love having them with me and I can't bear not having them there.
"They come backstage at 6.30 for tubby time and a story from daddy and papa. That's the ritual, and then they go back to the hotel and I go on stage covered in bubbles."
And he reaffirmed to presenter Norton his touring commitments would change hugely as his eldest Zachary reached school age.
"I will take him and pick him up. I'm going to make sure I am around. My touring schedule and my whole life will change, it has to," he said.
"It's all about my children and I want to give them a life with their parents. I'm 66 now and I don't have to tour. Having the children has changed my life and the way I think. I have never felt love like this.
"There's not a word in the dictionary that describes that love. Those kids have given me more pleasure in three years than I have had in the rest of my life."
Sir Elton also told of his delight that actor Tom Hardy had been cast to play him in a movie about his life.
"I've spent a lot of time with Tom already and we get on like a house on fire. We are very much alike - you wouldn't think so and certainly not physically. I wanted a serious actor and I'm so thrilled he is doing it," he said.
"I didn't want it to be a flippant film. It's based on fact but there is a lot of fiction in it because I don't want just the usual biopic and my life has been so surreal."
:: The Graham Norton Show is screened on BBC1 tomorrow at 10.35pm.