Like all great (and not so great) rock bands, The KLF defied the runes and came back. Albeit for 23 minutes. And it was a disaster. The single - 'Fuck The Millennium' - stalled at 28 in the charts on the back of its expletive-ridden text and its generally being, well, a bit rubbish. Its one and only live outing, presented in a multimedia spectacular (striking dockers, motorised wheelchairs) at London's Barbican, was delayed, falling as it did just two short days after our fairytale princess laid her lovely head to rest upon that Parisian pillar. Respect for the collective amnesia of our courtly mourning, Drummond claims - and because they knew there was more Dead Di to be scraped up than publicity if they went ahead that remarkable week. Cowardice had never before been a KLF trait. Perhaps that was the real point of the comeback: that somehow it was really Drummond's self-styled personal magic piloting that phantom white Fiat through the French capital that fate-filled night?

Personal magic is important. Drummond has ways of making things happen. His book is not subtitled My Crazy Rock Life. There are elements, of course, how could there not? Bill Drummond was up to his eyes in the Liverpool scene of the early 80s. The Bunnymen, Teardrop Explodes: you will find their stories and the stories Drummond wanted to tell. He is a great mythologiser. Hence the fanciful sketch for a novel about the last days of the Teardrops as a sort of glorified South American bar band, recording the two greatest LPs ever made before making one "marginally less good". As their manager, Drummond would be obliged to fly out to Bogota and "shoot Julian Cope in the head".

But that's not self-mythologising. Not really. For 45 ("nothing to do with the '45 rebellion or the Colt 45 or 45rpm; it was because I had subconsciously taken on board that the age of 45 is as good as it gets") is racked with doubt and introspection. Drummond is, he lets us know, a complicated man. Underneath The KLF's self-styled Stadium House lurked hidden agendas, ideas that allowed them to sculpt records like the monumental 'It's Grim Up North' and plot and execute the perfect novelty Number One ('Doctorin' The Tardis'). They even wrote a book telling you how to do it. And, on receiving a Brit as joint Best British Band (with Simply Red!), announcing that they were leaving the business: "Jimmy and I have always been eager to pose questions, never very good with coming up with answers."

The book's terms of reference are wide. He muses on nationalism and art. He visits Serbia, and records a soundtrack to his novel Bad Wisdom (co-written by Mark Manning) with a host of fictitious Finnish punk bands ('One Less Slag' by The Fuckers "celebrates" the Paris crash). Drives round and around the M25 in a truck with his mad Falklands vet pal Gimpo ("I am hoping to uncover some psychogeographical facts about both the ancient and modern roads and routes that radiate out of the unseen metropolis"). And he tours London on Christmas Eve, distributing free Tennant's Super to the homeless, including an amusing stint outside the Crisis shelter. Philanthropic to the last. Just don't ask why he and partner Cauty burnt a million quid and made a film about it. "This is an important statement we are making," he writes, "even if we don't know what it is ourselves."

Ferociously intelligent, sometimes poignant, often melancholic (though never nostalgic), 45 is a strange and wonderful book. There are elements of Iain Sinclair in his wandering, echoes of Will Self (although Drummond doesn't like Will Self) in 'My Modern Life,' a brilliantly sustained short story about visiting his local library.

"I want you the reader to realise," he says, "that I can stand outside myself and think, 'What an arsehole you are, Drummond.'" And you do begin to wonder after a while if the prankster in him won't pop up again a few years hence and giggle about all this is bollocks. He has created about himself a carapace of disarming deception; one scheme is described as being "a private joke that's so private I don't even get it myself". The Pop Life as fiction. Bill Drummond is a national treasure and 45 simply the best - and best written - book by or about a musician since Brian Eno's A Year With Swollen Appendices.