LONDON – Top U.K. talent agent and producer Addison Cresswell, who was part of a “comedy mafia” credited with making comedy the new rock and roll in Britain, has died at the age of 53.

“(Cresswell) was the best agent I ever dealt with, shrewd and sophisticated, and utterly devoted to his clients. He was a pioneer and one of the key figures responsible for turning comedy into the industry it is today,” Peter Fincham, director of television at leading U.K. commercial network ITV wrote in an article paying tribute to Cresswell in the Guardian newspaper Tuesday.

Cresswell repped some of the leading comedy talent in the U.K., and propelled them from the live comedy circuit into primetime TV slots, as well as securing lucrative home entertainment deals for them.

His best-known client was Jonathan Ross, who has a chatshow on ITV. Among his other “boys,” whose careers he defended fiercely, were Jack Dee, Lee Evans, Alan Carr, Michael McIntyre and Dara O Briain.

Cresswell’s skill as a negotiator was legendary, but that sometimes had unforeseen consequences. A groundbreaking 18 million pound ($29.5 million) deal he inked with the BBC for Ross was used as a stick with which to beat the pubcaster. The press accused the publicly-funded network of using ordinary folk’s hard-earned cash to line the pockets of celebrities.

Cresswell was a loyal friend and mentor to his clients, and a tireless worker for charity causes, such as London’s Great Ormond Street children’s hospital.

Interviewed for a Guardian profile of Cresswell in 2008, leading TV exec Kevin Lygo said: “With broadcasters, he can be volatile — but my experience with him is that he is straight, and you always have the feeling that he has his client’s best interests at heart. He has an understanding of television, and is a hard negotiator but also fair.”

For his part, Cresswell said of TV execs: “I don’t see us as in any way different from the people who run the channels. They’re complete bastards as well, but we all have to work with each other.”

His company, Off The Kerb Prods., said in a statement: “Addison will be fondly remembered by all whose lives he touched as a devoted mentor, a dear friend and an unforgettable character. He will be sorely missed.

“He is survived by his beloved wife, Shelley, his dogs Bonnie and Nessie and many, many pet fish.”