In February 1976, with his waistline on the up and up and his career in a serious downward slide, Elvis Presley recorded an album called From Elvis Presley Boulevard. Not that he wanted to: but the contract had been signed long before and, try as he might, he couldn't get out of it. Since the increasingly eccentric singer refused to travel, RCA was obliged to send a mobile recording studio to his Memphis mansion, Graceland, where the musicians had to scramble in through the windows of the house's "jungle room" and set up their gear amid its down-home decor: rabbit-fur throw pillows, fake-fur lampshades and a waterfall. Though he claimed to be too sick to work - and, at one point, produced a gun and threatened to shoot out the recording equipment - Elvis laid down a dozen tracks, of which 10 made it on to the finished album, in a week. As the RCA crew was packing up to leave, he had a final word with his producer, Felton Jarvis. "I'm so tired," he complained. "You need a rest," Jarvis replied. "That's not what I mean," said Elvis wearily. "I mean, I'm just so tired of being Elvis Presley."
As it turned out, he didn't have to carry the burden for very much longer. On the afternoon of August 16th 1977 the king of rock 'n' roll was found dead on the floor of his bathroom, giving rise, of course, to a thousand wisecracks about "falling off the throne". But if the king was dead, the bandwagon which called itself "Elvis Presley" was lumbering ever onwards. Twenty years on, it shows no sign of creaking to a stop - on the contrary, "Elvis Presley" has grown into an industry of mammoth proportions.
Since 1977, over 200 English-language books about Elvis have been published and 100 million copies of his records sold worldwide. In 1994 the Presley estate was estimated to be worth $100 million. Each year more than 700,000 people traipse, boggle-eyed, around Graceland, making it the second most visited house in the US after the White House. Elvis is still both an iconic figure in popular culture - check out this summer's trendiest film release, Men In Black, whose soundtrack features a brief but glorious thrust of Elvis overdrive - and a synonym for grimly poignant kitsch, as in Elvisly Yours, a memorabilia shop in the London suburb of Shoreditch where grieving fans can buy Magic Elvis watches with a picture of Elvis glowing eerily on the dial every 15 seconds.
Most revealing of all, perhaps, is the state of Elvis play on the Internet. Even the most cursory search reveals a plethora of Web sites - 135 turn up in a matter of seconds, including one which purports to show the star's life as seen through the eyes of his stillborn twin brother (in Dutch, alas) and one which lists forthcoming gigs by an Elvis impersonator called Melvis. Melvis, described as "the first openly Jewish Elvis impersonator outside of Israel", was planning - when he last updated his site in January 1996 - to bring to such venues as Pete's Pork Pie Place in Dade County, Florida and the International House of Pea Soup in Miami his rendition of well-loved Elvis standards like Blue Suede Jews.
Yet another web site lists "inspiring tales from the Oracle of the Plywood Elvis", an edifying edifice which stands in the garden of a private home in a small town in Montana. Believers who wish to share their oracular experiences range from Tony in New York, who declares that "in this crazy mixed-up world, it is comforting to know there is salvation in our king . . . you have changed my life and brought me the gift of spiritual guidance" to Edna in Sioux City, who reports: "Elvis told me to contemplate poultry and I found a diamond ring in my KFC mashed potatoes".
So potent a blend of the celestial and the commercial is, of course, quintessentially American, just as Elvis himself was an archetypical product of his time and place and his meteoric rise to international fame - achieved without his ever setting foot on a stage outside the US, apart from a five-concert tour of Canada in 1957 - can be explained, at least partly, in terms of a post-war generation hungry for a hint of rebellion and desperate for larger-than-life, Hollywood-style glamour. But how do you explain the existence of a Californian cult whose members believe that there are other Elvis fans in the outer reaches of the solar system, and hope some day to communicate with them?
And what about the sightings? The US supermarket tabloid Weekly World News carries regular spot checks on Elvis's whereabouts, and claims to be in possession of tapes which prove that he phoned President Bill Clinton: Elvis has been seen everywhere from a Burger King in Kalamazoo, Michigan to a Waitrose supermarket in the English town of King's Lynn.
In popular culture, it's true, those who die young often inspire retrospective adulation of a particularly feverish kind - but nobody claims to have seen Freddie Mercury lurking in the underwear department of Marks & Spencer or Kurt Cobain waving a Visa card at a DIY checkout. If you think about it, there could hardly be a less likely candidate for eternal life than the bloated, drug-sodden 42-year-old Elvis, who weighed anywhere between 250 and 350 pounds at the moment of his passing and whose blood on the night of his death, according to a post-mortem analysis carried out at a laboratory in Van Nuys, California, contained traces of codeine, quaaludes, Valium, Valmid, Placidyl, pentobarbital, butabarbital and phenobarbital.
Close scrutiny - and there has been plenty of it in the run-up to next Saturday's anniversary of his death - reveals that, like all the best cult heroes, not to mention all the great world religions, "Elvis Presley" can sustain a multitude of differing and sometimes diametrically opposed interpretations. Take the girls, for instance.
According to the myth, the greatest sex symbol of all time was also one of the greatest lovers of all time, with a parade of leggy lovelies vying for space in his bed and in his heart. Breathless "tell-all" biographies by a brigade of ex-girlfriends have gushed into print, of which one of the latest - June Juanico's Elvis: In The Twilight Of Memory (Little Brown, £15.99 in UK) contains page after page of the widdle-bitty baby-talk with which Elvis apparently liked to woo his harem of wide-eyed teenage fans.
Nauseating? Perhaps: but not, in any case, a patch on the more muscular anecdotes regurgitated by Peter Brown and Pat Broeske in their spine-tinglingly readable new study of Elvis's life and death, Down At The End Of Lonely Street (Heinemann, £16.99 in UK). With Elvis ensconced in the penthouse suite of a luxury hotel, it seems his aides would routinely be sent down to the foyer to instruct the management to open the doors to the crowd of girls who would inevitably be camped on the street outside; the aides would choose the prettiest, who would be ferried upstairs, some with their panties already in their hands; Elvis would take his pick, and the aides would inherit the rest. These "girl fests" were repeated on a nightly basis at his Los Angeles home.
Then there was Priscilla, seduced at 14, hidden away at Graceland when she was still under the age of consent and married as a tawdry publicity stunt, only to be discarded after the birth of Lisa-Marie because Elvis was disgusted by the idea of having sex with a woman who had had a baby.
"Something to do," said another partner who rocked and rolled on Elvis's bed for a while only to have him "go nuclear" when he discovered she was a mother of two, "with him thinking he would be having sex with his own mother". And Elizabeth Stefaniak, his "secretary", who was often summoned to spend the night with him after that night's girl had been sent packing; and Kathy Westmoreland, one of his backing singers, to whom he used to say, after sex, "it's time", meaning she should go to her own room because another woman was on the way. It may be only rock 'n' roll but it ain't, as the song should have said, no way to treat the ladies.
Brown and Broeske save their most devastating "Elvis Presley" demolition job for their closing chapters, in which they catalogue with pharmaceutical exactness the awful truth about Elvis's dependency on prescription drugs, and explode the mythical version of his death, which features a romantic dash to the Baptist Memorial Hospital in Memphis with his personal physician at his side, pleading "Breathe, Presley, breathe" as medical staff work desperately to resuscitate the doomed star.
In fact, say Brown and Broeske, it was obvious to all of Elvis's immediate entourage that he had been dead for hours when he was found toppled off the loo, "buttocks upward in the air, both feet splayed behind him . . . Blue streaks were spreading up through his face, and his hands, which were frozen into fists, were grasping the carpet fibres". Why the pretence? Because, they claim, if he had been declared dead at the house his body would have been taken to the morgue for an immediate autopsy and its contents, in turn, would have immediately been made public.
Sending him to hospital for emergency treatment effectively put his family in the driving seat, even if it did result in the unappetising spectacle of a medical team repeatedly applying electronic defibrillation paddles to a rapidly stiffening corpse.
But even Brown and Broeske, after 400 or pages of schlock horror revelations - including what they claim is "new" material which proves conclusively that it was a heart attack, not drugs, which killed Elvis - entitle their final chapter "Long Live The King" and mumble in a somewhat abashed tone about Elvis's generosity to charity, unstinting devotion to his fans and genuinely sweet nature. And we haven't even mentioned the music: those electrifying early tracks on Sam Phillips's Sun Records; the lithe beauty of that extraordinarily pure voice as applied to a simple gospel tune or an obscure Bob Dylan song like Tomorrow's A Long Time; even, dammit, the hothouse schmaltz of In The Ghetto. Twenty years after his death the worst of "Elvis Presley" may finally have been revealed in all its unwholesome physicality - but the best hasn't even begun to show its age.