Catherine, Princess of Wales was "nervous and apprehensive" before her first music festival, according to a royal expert.
The 41-year-old royal is reported to have danced the night away at the 24-hour Houghton Hall event after dining with her Norfolk friends, the Marquess and Marchioness of Cholmondeley, David and Rose, last weekend.
Catherine's trip to the music festival came after her husband Prince William enjoyed a night out in Koko club in Camden recently.
Speaking on the 'Palace Confidential' podcast, the Daily Mail's diary editor Richard Eden said: "I think Catherine may have thought, 'If [William] is going for a night out with his mates, why can't I'?'
"They've probably reached a point where they're getting a bit nostalgic."
Catherine is not known to have previously attended a festival, but enjoyed herself at Houghton Hall.
A reveller told the London Evening Standard: “(Catherine) was in high spirits, ordering spicy margaritas, eating affogato (an Italian coffee-based dessert), and speaking affably with the other members of her party.
“Her companions apparently carted in a huge, balthazar-sized bottle of AIX rosé and, together with Kate, left the festival restaurant staff a £700 (about R16,800) tip.”
A balthazar is a 12-litre bottle and is said to be worth at least £500.
Catherine was also said to have avoided the festival food trucks, instead apparently opting for the on-site Turntable and Napkin restaurant where guests pay £60 a head for a four-course feast.
Acts that played the festival included DJ Stingray, DMX Crew, Shanti Celeste, and Radioactive Man.
A source told the Daily Mail about Catherine’s decision to party at the festival: “After dinner, one of the guests suggested that Catherine go to the festival.
“Catherine was nervous about the idea, but, after much discussion with her protection officers, she went with lots of security. William wasn’t there.”
The upmarket Houghton Hall festival is billed as Britain's only 24-hour music festival and was created by DJ Craig Richards, who launched the event in 2017.
More than 200 artists performed across 13 stages this year, with music playing somewhere on the Houghton Estate site at all times.
More than 12,000 revellers were estimated to have attended.