By Alex Webb BBC News Online entertainment staff

Only those over 60 or so can remember a world without Elvis Presley, whose death 25 years ago is being remembered by fans all over the world on Friday.

The boy from Tupelo, Mississippi was, contrary to appearances, nearly penniless at his death and had to tour constantly to pay his enormous bills.

Now the man has made an amazing posthumous comeback, with A Little Less Conversation recently going to number one in 22 countries.

He had that amazing voice - which was sexy for women but reached guys as well

Doug Flett, songwriter

His music is being used in the latest Disney film Lilo and Stitch, and there are rumours that another remix, Burning Love, will be released in September.

Music journalist Karl Dallas, who wrote for Melody Maker for almost the whole of Elvis's career, told BBC News Online he was not surprised by the King's enduring appeal.

"Elvis had something which was both unique and very ordinary.

Presley: "A real person who moved his hips and sweated"

"He wasn't a manufactured product which all of the pop stars today - even the best ones - tend to be.

"What came through was his reality, his authenticity - he was very much himself, doing what he wanted to do and not being pre-packaged by a big record company."

Elvis first hit on his winning formula, a unique stew of country, blues and rock'n'roll, while messing around in the Sun Records studio in 1954 on a version of That's All Right Mama.

But unlike many of his generation he was also able to sing ballads, show tunes and gospel convincingly.

And like all great singers, he made each song he sang his own.

Elvis married Priscilla in 1967

"It has that authenticity, that feeling that this is a real experience being communicated by a real person who moved his hips on stage and sweated," remembers Karl Dallas.

"There was nothing phoney about Elvis, and even at his lowest point when he was recording forgettable music and making quite awful movies, there was still something that shone through."

To music journalist Charles Shaar Murray, the golden voice was part of an unforgettable package.

"The kind of iconic status Elvis has achieved is almost independent of his actual work or his cultural achievements," he told BBC News Online.

"Iconic status is an awful lot to do with how you look, and he was the prototype rock star.

Elvis got his second wind in the late 1960s

"But he was also an incredibly dynamic vocalist, with an instinctive ear for finding common ground between a lot of different musics.

"The fact that he looked a certain way, dressed a certain way and moved a certain way just made it perfect."

After the glories of his Sun hits and his early RCA recordings, Presley went mainstream with a vengeance in the 1960s, making dozens of films for MGM and recording many inferior works.

But, Charles Shaar Murray believes, Presley still cut some great tracks in his later years.

"He made great records at two or three stages of his career - the late 1950s and late 1960s particularly.

"Unfortunately he didn't really have the strength of character to pursue a musical muse outside what his management told him."

Providing some of the songs for Elvis in the second half of his career was the British songwriting team of Guy Fletcher and Doug Flett.

Elvis: "Exceptionally good looking"

The initial contact with Elvis was a matter of luck, Doug Flett told BBC News Online.

"In 1967 Guy and I had a song in the finals of the Eurovision Song Contest called Wonderful World - our publisher heard this song, was very impressed with it and got it to Elvis Presley.

"It appeared in one of those dreadful MGM films the poor man was forced to make."

But the Fletcher-Flett team soon got another call from Presley's management.

"We got a phone call some months later asking if we'd care to submit a song for his next album - so we worked furiously and came up with half a dozen songs and he recorded one of them, called The Fair's Moving On.

"We felt like old hands then, and the word came again to submit another song so we wrote a romantic ballad called Just Pretend."

Though the pair did not meet Elvis, Mr Flett, the lyricist, said he would never forget hearing the King singing his words.

Elvis performed frequently in Las Vegas in his last years

"It was thrilling, and when we heard the acetate recording - this was pre-cassette - we were stunned.

"The song fitted him like a glove - he was breaking up with Priscilla at the time, so there was that behind the music as well."

And Mr Flett has no doubt that it is Elvis's voice that has continued to reach hearts all around the world - 25 years after his death.

"He was exceptionally good looking, but he had that amazing voice - which was sexy for women but reached guys as well."

"And he invented rock'n'roll."