It is not an understatement to say that the British comedy world was rocked as well as shocked to hear yesterday that Addison Cresswell, one of the industry's most powerful agents, had suddenly died. He suffered a suspected heart attack in his sleep on Sunday night. He was 53. I think that the last time I saw him was at the British Comedy Awards earlier this month. I only caught a glimpse of him but he seemed to be his usual self, talking fifteen to the dozen to various comedy and media movers and shakers. 

Cresswell, who founded Off The Kerb management in 1981, was very much the power behind the throne of some of modern comedy's biggest stars, from Jonathan Ross and Lee Evans to Jack Dee. It could be said that he changed the face of modern comedy when he made Michael McIntyre a star, getting him onto high profile shows such as the Royal Variety Performance when he was relatively unknown, and turning him into a household name.

Off The Kerb has now issued a statement: "Agent, producer and charity fundraiser Addison Cresswell passed away in his sleep at home last night at the age of 53. He leaves behind a proud legacy in his tireless charity work, initiating and organising the annual C4 Gala in aid of Great Ormond Street Hospital. It was his dearest wish to raise enough to fund the opening of a brand new wing of the hospital, a goal that is now in sight.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."

Cresswell was a famous wheeler-dealer who negotiated Jonathan Ross's £18 million BBC chat show contract and made sure his artists got the rewards he felt they deserved. He had his critics, of course. There were those that said it was a little too cosy the way that his acts were regularly guests on chat shows presented by other Off The Kerb acts (he also handled Alan Carr), but there was always the explanation that his acts were such big stars if they had something to promote they would naturally be invited onto the chat show circuit.

He was as tough with the press as he was with the industry, but he did it in a charming way. When I asked for an interview with Ross at the height of his fame a few years ago I was told by one of his staff that Addison gets so many requests for interviews with Ross that he ignores all of them. But because he liked me he was at least replying to my request with a definite no. I was suitably charmed. Whenever we met he pointed at me, addressed everyone in his vicinity and said "Ain't he like the Manic Street Preachers" because of my very vague passing resemblance to lead singer James Dean Bradfield.

In a world of colourful characters he was as colourful as any of his acts, known affectionately as something of a cigar-chewing wide boy. Whenever I met him he was always friendly and always had a story to tell. Urban myths and the truth tended to blur together. One year at the Edinburgh Fringe he was in a mixture of panic and fury in the Assembly Rooms bar because an expensive ring had gone missing in his hotel room. In the end it turned out to be at the back of the safe. There was another story about him going to a Champions League match and getting drunk, only for it to turn out he had unwittingly been drinking alcohol-free lager.

At the same time he did his best to remain in the background. As the comedy boom took off a few years ago I proposed writing a book about the industry, inevitably entitled Funny Business. He would be the star of the book and I would follow him from festival to festival, meeting to meeting, over a twelve-month period. My request was politely deflected.

Cresswell might have seemed like a hard nut but appearances could be a little deceptive. When he started out in the mid-eighties putting on small gigs on the south coast when he was Entertainments Officer at Brighton Polytechnic he was decidedly left wing. He always did plenty for charity. As well as the O2's annual C4 Comedy Gala in aid of Great Ormond Street Hospital,  last week Michael McIntyre compered an Off The Kerb-promoted show at the Hammersmith Apollo in aid of Kids Company.  

He was fiercely loyal to his clients. He did not have any children with his wife Shelley and in a way his clients were his family. I remember one year I was chairing the Perrier Awards Panel in Edinburgh and the hotly tipped Alan Carr didn't make the shortlist. Cresswell called me when he got wind of the news and talked at me non-stop using every argument in the book to try to persuade me that the judges had made the wrong decision. He demanded, in the friendliest of ways, that Carr be reinstated. I reassured him that Carr would be a star anyway, and, of course, with Cresswell's guidance he was.

With Cresswell gone comedy has lost a crucial figure. Maybe the most important offstage figure in post-alternative comedy. Whatever one's thoughts about the comedy business, there is no doubt that Cresswell was central to making comedy the huge multi-million pound industry that it is today. Comedy will no doubt be a blander world without Cresswell.