A souvenir booklet from a royal party lists Jeffrey Epstein and Ghislaine Maxwell as guests at an event at Windsor Castle in 2000 by invitation of Prince Andrew.
On June 21, 2000, the couple attended the royal family's Dance of the Decades at the royal residence west of London.
The party held at Windsor Castle was to celebrate four royal birthdays - Prince Andrew's 40th, the Queen Mother's 100th Birthday, Princess Margaret's 70th and the 50th of Princess Anne.
The never-before-seen party programme obtained by the Daily Mail is a reminder of how close the pair were with Prince Andrew.
The guest list individually names Maxwell and Epstein separately.
During last year's iconic BBC interview with Prince Andrew, he claimed Epstein was only invited as Maxwell's "plus one".
However, royal protocol dictates only couples who are married or engaged be named together.
Maxwell says she and Epstein dated in the 1990s, however nothing more came of their relationship.
In the BBC Newsnight interview, Emily Maitlis asked the prince a question regarding the party.
"In 2000, Epstein was a guest at Windsor Castle and at Sandringham, he was brought right into the heart of the royal family at your invitation."
The prince replied: "But certainly at my invitation, not at the royal family's invitation but remember that it was his girlfriend that was the key element in this. He was the, as it were, plus one, to some extent in that aspect."
Later, in 2000, Prince Andrew invited Epstein and Maxwell to Sandringham for a "straightforward shooting weekend".
In March the following year, Virginia Guiffre claims she was forced to sleep with the prince for the first time, when she was 17, in Maxwell's London townhouse.
This is an allegation Andrew has categorically denied.
Musician Graham Dalby attended the party at Windsor Castle and told the Daily Mail it was "quite possible" Epstein could have danced with the Queen.
The swing band member said the Queen was in "great form", dancing with many guests.
"She was on such great form. The dancing was actually being fronted and being led by the Queen, I've never seen the Queen so animated, she had a really lovely smile on her face and she was wearing a lovely powder blue dress and she was looking absolutely stunning.
"She was just grabbing people and pulling them onto the dance floor.
"She nearly grabbed me and I thought 'ah don't grab me I can't dance' and she got the man next to me and he couldn't dance either."
Dalby told the Daily Mail he doesn't recall the prince being on the dance floor.
"Andrew's not a dancer so they [him and Epstein] would have been in a corner with a drink, talking, I suspect."
He is certain the Queen would have met friends her son invited to the event.
"Oh yes, and she would have made it her business to know who everybody was. I mean she knew who I was.
"I wouldn't have known who Epstein was, he wasn't known. I mean I recognised all sorts of famous people in amongst all the titles. Jackie Stewart the racing driver was there, but certainly that's not a man I would have gone, 'there's Jeffrey Epstein' because he meant nothing to me," he told the Daily Mail.
The following day, the prince, Epstein and Maxwell were photographed at Ascot.
Six years after the ball, Epstein and Maxwell were back at Windsor Castle as guests for Princess Beatrice's 18th birthday, where they were pictured in fancy dress alongside disgraced film mogul Harvey Weinstein.
The Queen and Duke of Edinburgh did not attend.
Prince Andrew has denied any wrongdoing.
Publicly, the US Department of Justice has said they would like to question the prince over his connections to the billionaire.