Prince Harry "jumped the fence" at Glastonbury and partied until 4am, the festival founder joked after he was knighted at Windsor Castle.
Sir Michael Eavis, 88, hosted the first festival on Worthy Farm, Somerset in 1970 and was honoured for services to music and charity on Tuesday.
Speaking after the ceremony, presided over by Princess Anne, Sir Michael said both the King and Harry had attended the summer festival before.
He said: "The King came once, Prince Charles. And Harry - I think he jumped the fence I should think."
Prince Harry jumped into Glastonbury back in 2013
PA / Getty
When asked how he knew this, Sir Michael chuckled and said: "I've got spies everywhere. No, I've got security all over the place actually."
He continued: "He enjoyed it! [The then] Prince Charles enjoyed it as well actually."
Regarding the Duke of Sussex's visit, the festival founder added: "He only came once.
"That was the old Prince Harry before he went to America."
Prince Harry (Grey Trilby hat) backstage at Glastonbury 2013 Festival
PA
In 2013, Prince Harry was spotted backstage watching The Rolling Stones headline the Pyramid Stage and partying until the early hours of the morning with Sir Michael.
Speaking at the festival that year, the festival founder said: "Prince Harry was great actually.
"I recommended that he should go on into the night because the nightlife is what Glastonbury is all about.
"At three o'clock in the afternoon, you don't get it.
Cressida Bonas, Prince Harry's ex-girlfriend, attending 2013 Glastonbury Festival
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Bar Boulevard, where Prince Harry was seen during Glastonbury 2013 Festival
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"I told him to get his taxi driver to come back at five o'clock in the morning and do you know what? He lasted until four in the morning.
"His friends were all having a great time. He didn't want to make a formal thing of being here."
Greenpeace, Oxfam and WaterAid all receive donations from the festival.
The event aims to raise around £2million per year, which also helps hundreds of local causes.
GB News has approached the Duke of Sussex for comment.