Main image by Terry O’Neill. Hand colouring by David Bowie

Before a word has been spoken, I'm in pieces. The press launch for the V&A's forthcoming exhibition David Bowie Is, launching on 23rd March 2013 and running for four months, features a handful of items to titillate the fascination of the assembled hacks, and the very first - an exercise book featuring handwritten first drafts of soon-to-be-classic songs, is already enough to bring a tear to the eye. There in Biro, in the Dame's disjointed, almost adolescent hand, are the words to 'Five Years', the mere sight of them causing his voice to sing out in my mind: "All the fat skinny people/All the tall short people/And all the nobody people/And all the somebody people/I never thought I needed so many people..."

For the real, next-level Bowie nerd, there's the revelation that "favourite melody" was originally plural (before he thought better of it and crossed it out), and "wheels of a Cadillac" originally "wheels of a tram". From the sketchy first run at "Fame" on another page, we learn that it originally went "makes you play loose" (not "makes you loose"), and "what you like" (not "what you need").

Glance up from the glass cabinet, and you're in fanboy heaven, confronted with mannequins wearing three iconic Bowie outfits: the Natasha Korniloff Pierrot suit and cone hat from Scary Monsters, Alexander McQueen's Union Jack coat from Earthling, and - most arrestingly of all - Freddie Buretti's garish jumpsuit and cherry red bovver boots from the Ziggy era (intended to echo A Clockwork Orange but with the aura of violence diffused by the Laura Ashley pattern), so familiar from THAT endlessly repeated 'Starman' TOTP clip. Stood next to it, you deduce that Bowie must be surprisingly short. They always are.

Design by Kansai Yamamoto. Photograph by Masayoshi Sukita

If this brief encounter with a few selected excerpts is mind-blowing for a Bowie fan, then David Bowie Is promises to be truly out of this world. The man himself was not involved in curating the exhibition, but granted curators Victoria Broackes and Geoffrey Marsh unique access to his carefully-annotated archive in New York. This, explains the museum's Damian Whitmore, is "the V&A's take" on Bowie, and will be "much more than a costume exhibition", reflecting Bowie's "creative genius across all media".

Broackes insists that simple nostalgia is not the aim, and that David Bowie Is, sponsored by Gucci and Sennheiser, puts Bowie "firmly in the present tense". Rather than follow a simple timeline, it will take a thematic approach, looking at topics such as Bowie's self-confessed love of "taking High Art and demeaning it to street level" (Ziggy's debt to Kabuki theatre, for example, and Diamond Dogs' to Orwell and Fritz Lang), the way in which "his radical individualism acts as a catalyst for self-expression among his fans", his interactions with other artists (William Burroughs, Christopher Isherwood, Klaus Nomi) and his influence on the politics of gay liberation.

Seldom or never-seen highlights will include Brian Eno and Peter Schmidt's 'Oblique Strategies' idea cards (as used on 'Fame'), Burroughsian cut-up fragments of lyrics ('Blackout' from "Heroes"), Bowie's own felt tip-doodled storyboard for the 'Ashes To Ashes' video, unseen photos from the Diamond Dogs tour and a never-shown film, also from that tour, of a concert at the Tower Theatre, Philadelphia.

Designed by Fifty Nine Productions, the company responsible for Damon Albarn's Dr Dee opera and many of the more spectacular effects at the Olympic opening ceremony, the exhibition and accompanying hardback book has input from a seriously impressive array of experts including Paul Morley, Camille Paglia, Christopher Frayling, Jon Savage and Mark Kermode. Perhaps the most reassuring thing to come out of the press conference is that the only person all morning who mispronounces the great man's surname is a sniffy bloke from the Telegraph who thinks the V&A ought to be concentrating on the likes of Michelangelo instead of dirtying its hands with modern populist fare like this. (If you don't know that 'Bowie' rhymes with 'snowy', you probably shouldn't be allowed anywhere near pop culture.)

Design by David Bowie, film stills by David James

Two and a half years in the making (once Bowie had granted his "fairly swift" consent), it isn't finished yet: the curators are working with Bowie's old school in Bromley on a special project, and the run will also feature a Bowie film season and an academic symposium involving some of Bowie's more prominent collaborators.

Will Bowie himself show up? "He's fairly reclusive now", says Victoria Broackes, "and he doesn't fly". Maybe he'll just sit tight in New York and wait for it to come to him: after its London run, the exhibition will tour the world.

Design by Alexander McQueen with David Bowie

Tickets for David Bowie Is are on sale now at www.vam.ac.uk