His stage shows were simply incredible, always full of energy and inventiveness.
The Guardian reports Campbell was last on stage just days ago, where his Showstoppers Musicals at the Edinburgh festival turned fictional newspaper reviews into one-off pieces.
It was the latest in a series of Campbell's increasingly innovative improvisations, following on from his 2005 Improvathon, an experimental attempt to perform a 36-hour play without a script.
"The theatre and entertainment world has lost an extraordinary man," commented his friend and PR guru Mark Borkowski. "Ken was a dear friend. The world will never be the same."
Speaking today to Whatsonstage.com, Nicki Stoddart, one of Campbell’s representatives at United Artists, said: “Ken was a one-off. And he was a delight, such a bright and intelligent man. We represented him for many years and never ceased to by amazed by his imagination, exuberance and intelligence.
"His death is totally shocking and extraordinarily sudden.”
Ken, perhaps best known for the Ken Campbell Roadshow which he founded in 1971, worked with the likes of Bob Hoskins and Seventh Doctor Who Sylvester ("The Human Bomb") McCoy.
Coincidentally, he was consdered for the role of the Seventh Doctor. In an interview later, then then script editor of Doctor Who, Andrew Cartmel, said that Campbell’s interpretation was “too dark” to put on television.
A fan of sci-fi and the paranormal, in 1976 he set up the Science Fiction Theatre of Liverpool in 1976, which put on a series of spectacular shows, including Douglas Adams' The Hitchhiker's Guide to the Galaxy (he played Poodoo in the radio version), the eight-hour Illuminatus! (co-written by Chris Langham, which starred Jim Broadbent,), and the 22-hour The Warp, which had a set designed by Tim Albery.
His screen credits included roles in films such as A Fish Called Wanda and, on TV, parts in Fawlty Towers, The Professionals, The Bill, Heartbeat, Fantasy Island, Minder, Bulman and Law and Order. He also presented Channel 4 TV shows on science and the paranormal.
For all his love of scifi, he was not one for its real world trappings. "In the forlorn hope of trying to get Ken into the digital age, his daughter had gifted him a sum of money to buy a computer," Borkowski recalls in his tribute." Unfortunately the computer shop Ken was sent to had a pet shop next door. Instead of leaving the PC emporium with a laptop, Ken was lured into the pet shop only to buy an African grey parrot called Doris..."
• Official Website (under reconstruction)
• More about Illuminatus