It is not the only time this year that Bowie-lovers have thrown him a party only for the guest of honour's chair to remain empty. Although he hasn't toured for eight years, or appeared on stage in any capacity for six, it still seemed possible that he might make an exception for the closing ceremony of the Olympics to perform his yearning 1977 hit Heroes, the unofficial Games anthem.
On the night, a video montage of his singles ramped up the excitement before the arrival of… some supermodels on trucks. Such a conspicuous absence seemed to confirm what Bowie-watchers have suspected for years: that he has in fact retired but simply neglected to tell anybody.
Out of sight he may be, but never out of mind. A book about a single Top of the Pops appearance, Bowie's groundbreakingly homoerotic performance of Starman in 1972, has just been published. A new plaque in London's Heddon Street marks the 40th anniversary of Starman's mothership album, The Rise and Fall of Ziggy Stardust and the Spiders From Mars. Rock critics Paul Trynka and Peter Doggett have both written chunky studies of his life and work. His influence continues to be felt in the work of legions of younger artists, from LCD Soundsystem to Lady Gaga. In fact, Bowie love is at such a pitch that were he to announce a new tour tomorrow, he could set up camp at the O2 for weeks.
One reason for this undying fascination is that at a time when many feel that pop's past is a great deal more compelling than its future, Bowie's 70s career represents the white-hot thrill of innovation. The Beatles may have shown that it was possible to reinvent your music with every album but Bowie went one better by reinventing the whole package.
In the early 60s, the teenage David Jones spent a year as a "visualiser" at a Bond Street advertising agency and learned the dark arts of brand communication. His first album, David Bowie, was derivative, theatrical and easily ignored; even the chart-topping success of 1969's Apollo 11 cash-in Space Oddity made him look like an opportunistic one-hit wonder.
So, frustrated by the failure of even 1971's brilliant Hunky Dory to give him the stardom he craved, he remade himself as Ziggy Stardust, described by Peter Doggett as "the perfect rock'n'roll star… male and female, king and queen, alien and human, transcendental and sublime". While many rock musicians were sprouting beards and moving to the country in search of something "real", he was fabulously other: a physical realisation of his audience's most outre pop fantasies.
Most artists would have considered this a job well done and kept on going, but Bowie soon believed that Ziggy had mutated from liberator into jailer and killed him off after just 18 months. With each subsequent album, he became someone new: "cracked actor" (Aladdin Sane), apocalyptic seer (Diamond Dogs), "plastic soul" star (Young Americans), frozen-hearted Thin White Duke (Station to Station) and, on his trilogy of albums recorded in Berlin with producer Tony Visconti and new pal Brian Eno, the pale grandmaster of art-pop alienation. The philosophy is right there in many of the song titles: Changes, Station to Station, Move On.
His restless hunger made him one of the few 70s stars whom the insurgents of punk admired rather than mocked, while the sounds and themes of his Berlin period inspired every synth-pop act worth its salt. More broadly, his self-refashioning and magpie eye define pop stardom to this day. For each new concept, he hoovered up raw material from cinema, theatre, fashion, literature and visual art; the V&A exhibition takes in everything from kabuki to German expressionism to the Theatre of Cruelty.
Crucially, his shrewd pilfering was rooted in ceaselessly great songwriting. Tony Visconti recently talked about Bowie's unnerving habit of coming into the studio with mere sketches for songs and finishing them on the hoof. "It's a scary situation," the producer said. "I was never comfortable with it but I didn't have a choice. If this is the process, you go with the flow. Bowie remains to this day the most extraordinary person I've ever worked with in the studio, on many levels. He's always full of surprises. You can never predict what he's going to do."
Of course, this kind of creative velocity doesn't stem from contentment. Bowie could be anybody except, it seemed, himself. "Sometimes I don't feel as if I'm a person at all," he confessed in 1972. "I'm just a collection of other people's ideas." In 1997 he told Q magazine: "I had enormous self-image problems and very low self-esteem, which I hid behind obsessive writing and performing… I was driven to get through life very quickly… I really felt so utterly inadequate. I thought the work was the only thing of value."
In some ways, he was a weathervane for a decade in which many people were fearfully searching for answers – he was far from the only confused soul in the 70s to acquire an interest in the occult or an ambivalent fascination (later regretted) with fascism. But in his recent book The Man Who Sold the World: David Bowie and the 1970s, Peter Doggett suggests that Bowie was driven by a terror of losing his mind, as his older brother, Terry, had done.
In 1993, Bowie told the BBC: "I felt that I was the lucky one because I was an artist and it would never happen to me. As long as I could put those psychological excesses into my music and into my work, I could always be throwing it off."
He came closest to unravelling himself in Los Angeles in 1975 while making Station to Station, an experience he claims he can't (or chooses not to) remember in any detail, although he has admitted to living on a diet of cocaine, Gitanes, peppers and milk. This is a cherished bit of trivia because fans generally prefer self-destructive genius to well-adjusted mediocrity: never mind the life, give us the work.
The fitter and happier Bowie became during the 80s, the worse his music, leading to such fan-scarring horrors as the 1987 Glass Spider tour, the humdrum hard rock band Tin Machine and his mystique-annihilating duet with Mick Jagger on Dancing in the Street. It says something about his waning powers that his most worthwhile 80s creation after Let's Dance was the goblin king Jareth in the film Labyrinth.
More unjustly, boldly experimental 90s albums such as 1. Outside and Earthling were overlooked and only with Heathen, his 2002 reunion with Visconti, did he win back some of the warmth and acclaim that used to be his for the asking.
You wonder if this born neophiliac (he was an early champion of the internet and has long been a generous supporter of new bands) grew tired of living in the shadow of his youthful achievements and had no interest in the lucrative but repetitive hits tours embraced by so many of his peers. It has also been suggested, given that his 2004 world tour was curtailed by an emergency angioplasty, that his health would not permit a return to live performance. Or perhaps the reason for his apparent retirement is simple: perhaps he is just happy.
He lives in New York with his wife of 20 years, cosmetics entrepreneur and former model Iman, and their daughter, Alexandria. He is on good terms with his son, once known as Zowie Bowie, now as gifted film director Duncan Jones. He enjoys attending gigs and dining with old friends such as Visconti and Lou Reed. It's a fallacy to assume that any celebrity who chooses to retreat from the public eye must be a frail recluse, but by all accounts Bowie is comfortable and contented, so why not view his creative silence as a dignified victory rather than a form of defeat?
Much as his admirers may want him back belting out the likes of Heroes and Starman in the world's arenas, it might be fairer to accept that the man whose youthful genius was nourished by so much loneliness and self-doubt deserves the quieter, happier life he has built for himself. David Bowie has done as much as anyone to shape our understanding of what pop music can be. Surely that is more than enough.