Milligan was given an honorary knighthood last year
Prince Charles led the tributes to Spike Milligan after the comedian's death at the age of 83 from liver failure, saying he was "deeply saddened" at the news.
A statement from him read: "It is hard to see Spike's parting as anything other than the end of a great era of British comedy, exemplified by Spike's extraordinary genius for the play on words and for the art of the nonsensical unexpected.
"His particular form of hilarity and wit has provided countless millions with the kind of helpless mirth which adds unique value to life."
Prince Charles had been a fan of the comic since Milligan's days on The Goon Show, an irreverent radio comedy show from the 1950s.
The two first met when Charles became the Prince of Wales in 1969 .
They enjoyed a close friendship over the years, despite Milligan's comical outbursts against the prince.
In 1994, after Charles had written a letter congratulating Milligan on winning a lifetime achievement award at the British Comedy awards, the comic labelled him a "grovelling little bastard".
Sorry
He later apologised to the prince, writing a fax to him saying: "I suppose a knighthood is out of the question."
Soon after Milligan told an interviewer: "He (Charles) wrote back saying, 'I'm sorry, all the New Year's knighthoods are full up, but try a little light grovelling and one might come your way'."
Last year Milligan, who was made a CBE in 1992, was given an honorary knighthood - he had an Irish passport so he could not be given a full knighthood.
During the service the comedian joked: "Do you know there are no dry cleaners in Peru? I thought the statistic would interest you."
"Well, that is something," the prince replied.
The prince, who was named patron of the Goon Show Preservation Society in 1998, wrote the forward to some of the Goon Show's books of radio scripts.
The society's spokeswoman at the time said that he could mimic the show's characters "brilliantly".
But there were areas where the two men seriously disagreed - Milligan compared hunting and other bloodsports to murder, and Charles was unlikely to have appreciated the comedian's description of the Queen as uncharismatic, with a "cold voice".
In the end their friendship endured and the prince once said of Milligan: "He has made me laugh for more years than I can remember."