Ken Campbell was an actor, a writer and a comic one-man performer whose maverick experimental shows brought him acclaim and a devoted following but whose eccentric, highly individual approach caused the theatre establishment to regard him with some suspicion.

He came to prominence in 1971 with The Ken Campbell Roadshow, a chaotic evening of dotty and surreal storytelling performed in pubs, clubs and theatres by himself and a small group of actors including Bob Hoskins and Sylvester McCoy. Years later McCoy beat Campbell in auditions for the role of the seventh Doctor Who on television, Campbell’s interpretation being considered “too dark”.

It was with two extraordinary epic dramas, however, that Campbell made his name. Illuminatus! was a satirical tour d’horizon through several conspiracy theories laced with magic, sex and drugs. It consisted of five plays, whose running time was eight hours, and was based on a science fiction trilogy by Robert Shea and Robert Anton Wilson. At its first performance in a warehouse in Liverpool the audience was entertained by the novelist Brian Aldiss during the many intervals. It went on to open the National Theatre’s Cottesloe auditorium and the prologue was spoken by Sir John Gielgud.

With the bit firmly between his teeth, Campbell surpassed even this in 1979 with a ten-play flight of fancy at the Everyman, Liverpool, lasting 22 hours — The Warp, by the poet and painter Neil Oram, in which a search by the protagonist for his female side takes him from 15th-century Bavaria to a symposium on flying saucers in the 1960s. There were two one-hour intervals for meals and a half-hour break for beer, sausage and coffee at 2.30am. Jim Broadbent and Bill Nighy took their turns among a cast of clowns, fire-eaters, a comic postman, a bellicose landlord, Turkish policemen and Chinese bureaucrats.

“It was in the Guinness Book of Records as the longest play ever,” Campbell said. “The audience actually increased during the night as people rang up their mates. So did the musicians, as players came over after they had finished their gigs. We started with a jazz quartet and ended up like Duke Ellington.”

Campbell’s puckish, anarchic approach to life manifested itself in 1980 in an embarrassing hoax that he played on Trevor Nunn, then at the Royal Shakespeare Company. Nunn had enjoyed a huge success with Nicholas Nickleby and invitations, purportedly from him, were issued far and wide to join a new “Royal Dickens Company”, the offers made all the more plausible by being signed, “Love, Trev”. Nunn summoned the police and Campbell owned up. Not surprisingly, the two fell out, but they eventually made up and Nunn, by then at the National, commissioned Campbell to write The History of Comedy Part One: ventriloquism. Campbell was proud of his appointment as professor of Ventriloquism at RADA in 1999.

Kenneth Victor Campbell was born in 1941 in Ilford, Essex, to Elsie (née Handley) and Anthony Colin Campbell, a telegrapher. He won a scholarship to the fee-paying Chigwell School and left at 17 to study at RADA. “You had to say you were 18. I got in on my audition of a speech from Twelve Angry Men,” he said. After two years he joined Colchester Repertory Theatre.

He was subsequently engaged for a time as a straight man by Dick Emery, but upset the comedian while on tour by winning an unscripted laugh. “I’m the comedian,” said a furious Emery, pouring coffee into Campbell’s lap.

Campbell then became the director of the Bournemouth Aqua Show which consisted of stunt divers and mermaids. “I was in charge of the shallow-end acting bit,” he said.

His career as a playwright began tentatively in 1964 when he showed Warren Mitchell, whom he was understudying in the West End, a script that he had written called Events of an Average Bath Night. Mitchell liked it and performed in it at RADA.

Lindsay Anderson invited Campbell to join the Royal Court as a junior director in 1969 after the young tyro showed him a play that he had written about the highwayman Jack Sheppard. But Campbell felt obliged to quit when Anderson took over the direction of his first show. He created the Road Show at the Bolton Octagon. Its success brought him back to the Royal Court and he co-wrote The Great Caper, with Ion Alexis Will, a play about a search for the perfect woman through Europe and Lapland which starred Warren Mitchell.

In 1976 Campbell and Chris Langham formed the Science Fiction Theatre of Liverpool to put on Illuminatus!. Acting alongside them were Jim Broadbent, David Rappaport and Prunella Gee, Campbell’s wife, who played a guerrilla. The Science Fiction Theatre also produced a version of The Hitchhiker’s Guide to the Galaxy with Langham as Arthur Dent. In the celebrated radio version of The Hitchhiker’s Guide Campbell played Poodoo, a part written specially for him.