They were being joined by famous faces from the worlds of politics and showbusiness, including Michael Parkinson and Joanna Lumley.
Charles was joined by Frost’s widow, Carina Fitzalan-Howard, to lay flowers on a memorial stone dedicated to the broadcaster who died last August aged 74.
Ronnie Corbett, who worked with Frost in the 1960s satire boom that launched both their careers, was among those reading prayers during the service.
The service reflected the humour and satire which ran through his career with a comic tribute from Lumley called A Sonnet Of Sorts For A Star, which she co-wrote with musician Richard Stilgoe.
It began: “Shall I compare thee to Sir Robin Day? Thou wert more lovely and more temperate. Earth has not anything to show more fair, Hello, good evening, welcome, Frosty’s there.”
The humorous tribute included the lines: “No more TV-am, no Al Jazeera — We end not a career, but end an era; For now he’s gone, ascended into orbit, And ’I look up to him’ (quoth Ronnie Corbett).” It concluded with the line: “When Frost has gone, can spring be far behind?”
Known for his incisive interviews — above all, with disgraced US president Richard Nixon — Frost spent more than 50 years as a television star.
His award-winning interview style was considered non-aggressive, affable and effusive, but he had a talent for extracting intriguing information and revealing reactions from his subjects.
The memorial was a star-studded affair, attended by Pippa Middleton, Rowan Atkinson, Michael Caine and Sienna Miller.
Among those who came to pay tribute were funnyman David Walliams and his wife, model Lara Stone, as well as Julian Fellowes, Terry Wogan, Claudia Winkleman, Sue Lawley, Esther Rantzen, Stephen Fry, Anne Robinson, John Sergeant and Angus Deayton from the world of television.
Sergeant said: “It was like the last of the great Frost parties. It was perfect for him, absolutely perfect.”
Guests from the political sphere included Cherie Blair and Sarah Brown.
Former BBC director-general Greg Dyke drew laughter when he said that when Carina, before she became his wife, was asked after she first met Frost whether he was a religious man, she replied: “Oh yes, he’s very religious. He thinks he’s God.”