Shadow Warrior
by David McTaggart
240pp, Orion, £18.99

This is the confession of a man who wants to be seen as a heroic figure but who has to admit he has been mean - not least to his five children by four badly treated women.

David McTaggart died last year, aged 68, in a head-on car crash just as he was completing his autobiography. The crash was probably caused by a heart attack after a life of smoking, drinking and living hard. It was an extraordinary life - as one would expect of the man who created Greenpeace International and moulded it into an organisation which became feared by corporations and politicians for its ability to embarrass them.

Despite his knack of generating fantastic publicity, particularly in the years when he practically ran Greenpeace as a one-man show, McTaggart was a surprisingly shadowy figure. At a conference of the International Whaling Commission in Glasgow 10 years ago, when Greenpeace was at the height of its influence, I watched him walk into the meeting of commissioners arm in arm with the head of the Spanish delegation. He was in theory not allowed in, but nobody challenged him, and no one else recognised him either. Even the half dozen or so Greenpeace staffers lobbying the meeting let him walk by without a hint of recognition. He may have been a living legend in the organisation of which he was still honorary international chairman, but not one of them knew who he was.

I first met him 10 years earlier to interview him for the Guardian when Greenpeace had its international headquarters in Sussex. It was a hopeless exercise. Despite his apparent swashbuckling role, he was very shy about himself. He also knew that the tabloids could have had a field day with his private life. He would not talk about anything, except the (to me) irrelevant fact that he had once been Canadian badminton champion. It is something that is referred to again and again in the book - life's battles are likened to a badminton match.

But although it was a thin interview, he must have thought I had passed some kind of test because he began to pass stories, and some interesting documents, my way. And to cement the relationship, when he turned up from nowhere there would be conversations over many drinks. In between the serious matters he would tell very tall stories about what he had been doing. It was impossible to know which were true and which (to use one of his favourite expressions) were pure bullshit.

Even reading this book, a racy account, full of incident, there is an element of doubt. Some of the events I was reporting at the time: I was, for instance, standing side by side with McTaggart on a yacht off Mururoa to protest about French nuclear testing in 1995, and my memory doesn't tally with this account. His long-suffering friend, Pete Wilkinson, who ran Greenpeace UK and wrote the foreword to the book, agrees.

So do we find out about the real McTaggart in this entertaining account of his life? We certainly find out a lot more than we did before his tragic death. We are given a detailed account of his bad behaviour with women, followed by a series of apologies to both the women and the children he mistreated, mostly by simply failing to turn up to be a father.

It is hard not to dislike him for that, but there is something engaging about the rest of him. He is frank about his failings, his long-suffering parents and the anchor role of his brother Drew, to whom he always turned in trouble. By the time we get to the Greenpeace bit he is three times badminton champion, pushing 40, with two broken marriages behind him, and going nowhere.

The first altercation with the French off Mururoa changes his life. The desire to win that made him a champion finds a new game worth playing, with an opponent against whom he can pit his wits.

The battle effectively lasts the rest of his life - not just with the French but with the nuclear industry, those who slaughter whales, and general despoilers of the environment. He reinvents himself and his organisation repeatedly - as a David versus Goliath in many forms - and always with plenty of photographs and television film of the action. When his virtual dictatorship ended, and he was moved upstairs to an honorary role in Greenpeace, he argues that the bureaucrats took over and the organisation suffered. There is certainly truth in that.

Another revelation in the book is his close ties with Sir Peter Scott, Sadruddin Aga Khan and Mikhail Gorbachev - all in one form or another recruited to his cause. The Russian link is perhaps the most curious because it enabled him to establish a Greenpeace branch in Moscow when all other non-governmental organisations were still banned. He attributed his success in Russia to his ability to drink vodka, a typically vague explanation of what actually happened. It may be, of course, that he never understood it himself.

· Paul Brown is the Guardian's environment correspondent.