Joan Rivers and Prince Charles: Inside Their Unlikely Friendship
09/06/2014 AT 05:00 PM EDT
Like millions around the world, Charles, 65, and his wife, Camilla, Duchess of Cornwall, expressed sadness about her death on Thursday. For Charles, who since his youth has been a fan of zany humor, Rivers was one of those often-edgy performers who put a smile on his face, regularly joining him at fundraisers or for events at his country home.
She was a guest at his wedding to Camilla in 2005, and when he turned 60 three years later, she was a performer at a birthday gala (called We Are Most Amused) that raised money for his Prince's Trust charity.
Charles said in a statement Friday that the comedian, who was rushed to the hospital on Aug. 28 after she stopped breathing during an outpatient procedure, "was an extraordinary woman with an original and indefatigable spirit, an unstoppable sense of humor and an enormous zest for life. She will be hugely missed and utterly irreplaceable."
Said to have been introduced while on a painting holiday in the South of France in 2003, Rivers, who was a guest at the prince's country home, Highgrove, told PEOPLE last year about how they became friends. "We sat next to each other at a dinner party and got friendly," she said. "He's darling."
Charles is well known to have a "goonish" sense of humor and performed onstage with the Footlights Dramatic Club while attending Cambridge University. He was also a fan of the iconic British radio and early television comedy The Goon Show that starred Peter Sellers and Spike Milligan.
Friends also say he loves to be surrounded by funny people. "It just shows he is not a waxwork dummy – he has a great sense of humor," a family friend tells PEOPLE.
And former chief executive of the Prince's Trust, Sir Tom Shebbeare, tells PEOPLE, Charles was "a big fan" of Rivers. "She was a riveting personality and he found her very funny," he says. "He found her very irreverent, anti-establishment – and her being like that around the epitome of the establishment such as the royal family was daring."
Longtime chronicler of the royal family Judy Wade says, "She managed to get away with her humor even around the most respected people like members of the royal family. Charles would take any humor in the spirit it was offered."