MICK Jagger might rethink the words he sang more than 45 years ago - What a drag it is getting old.

Yesterday marked 50 years since Jagger, 68, played his first gig with a band called the Rolling Stones, and the group is marking its half-century with no let-up in its productivity or rock 'n roll style.

Jagger himself is still the cool, rich frontman of the world's most successful rock band.

Now in their late 60s and early 70s, the band members are celebrating the anniversary by attending a retrospective photo exhibition at London's Somerset House - and looking to the future by rehearsing for new gigs.

Jagger, Keith Richards, Ronnie Wood and Charlie Watts are getting together after the young R&B band first played together at London's Marquee Club 50 years ago.

The line-up for the gig was vocalist Jagger, guitarists Richards and Brian Jones, bassist Dick Taylor, pianist Ian Stewart and Mick Avory on drums. Taylor, Stewart and Avory soon left the line-up, drummer Watts joined in 1963 and guitarist Wood in 1975.

The band had its first hit, a cover of Chuck Berry's Come On, in 1963, and soon became one of the world's biggest and most influential rock acts, rivaled only by The Beatles.

The Beatles split up in 1970, but the Stones are still going strong - something Jagger says he could never have imagined at the time.

"Groups in those days and singers didn't really last very long," Jagger told the BBC. "They weren't supposed to last. It was supposed to be ephemeral. It was really only Elvis and The Beatles that were the biggest things that ever happened in pop music that I can remember. But even Elvis had lasted perhaps less than 10 years, so how could anyone really last?"

Music critic John Aizlewood said the Stones' contribution to rock 'n roll is "immeasurable". "They are a founding father of rock music as we know it," he said. "Other bands have tried and not pulled off that amount of sexiness, allied to a kind of street-fighting menace."

The Stones have sold more than 200-million records, with hits including (I Can't Get No) Satisfaction , Street Fighting Man and You Can't Always Get What You Want . But in recent years much of their income has come from touring. Their last global tour, A Bigger Bang , earned more than half a billion dollars between 2005 and 2007. And more live shows are on the way.

Richards said the band had begun rehearsing, but dates haven't been fixed.