* Veteran rockers headline at Glastonbury
* Mick Jagger, 70 soon, has no plans to quit
* Billy Bragg, Elvis Costello among day's lineup
It might only be rock'n'roll but, 50 years on, Mick Jagger still likes it - and insists he will keep going as long as fans want to see the Rolling Stones, set to headline the Glastonbury festival on Saturday.
Jagger, who turns 70 next month, said the once-controversial band still had comment to make on what was going on in the world, even if its voice seemed tamer than it once did.
He said the Rolling Stones actually never set out to make waves in the 1960s, when their drug use, love tangles and rebellious stage attitude shocked audiences and the band was blamed for fuelling social unrest and falling moral standards.
"We just set out to be a blues band and just behaved as we always had and like kids always behave," Jagger told BBC's Radio 4 Today show on Saturday, ahead of the Stones' debut performance at Glastonbury.
"We were sort of sidetracked into this social thing by the mood of the times and of the times themselves, which were galloping on," he said.
"The last song that I wrote, that I put out, called 'Doom and Gloom' is actually mostly social comment. It's very tongue-in-cheek social comment but it's still social comment," he said.
The Rolling Stones's appearance at Glastonbury, the world's largest greenfield music festival, comes as the band celebrates 50 years in the music business, which involved a North American tour this year and some sell-out dates in the UK this summer.
Festival founder Michael Eavis, who started Glastonbury as a gathering of about 1,500 hippies on his farm in 1970, has publicly delighted in finally persuading the band to play the festival that now attracts 135,000 fans or more.
As the headline act on Saturday, the Rolling Stones will top a day that also includes performances by Billy Bragg, Elvis Costello, Primal Scream and Noah and the Whale.
Glastonbury is known for megastars but also for variety, with 2,000 acts on 58 stages over the three days.
Some of the more surprising acts this year include U.S. country music star Kenny Rogers, octogenarian British TV presenter Bruce Forsyth and a group of chanting Tibetan monks.
In the lead-up to the festival, Jagger tweeted that he would be staying in a yurt, a Mongolian-style tent, at Glastonbury, where a working farm turns into a tent city for five days, but his location remained a secret ahead of the band's performance.
Asked if his hyperactive stage performance tired him now that he is knocking 70, Jagger admitted, "occasionally", but said he had no plans to quit and would go on as long as people wanted.
But while still enjoying his career, Jagger said he had wondered in the past about doing something else, such as dancing, being a teacher or even a journalist.
"I don't feel frustrated ... but obviously, you would have liked to have done, everyone wants to have done, more things in their lives," Jagger said.
"But it's a slightly intellectually undemanding thing to do, being a rock singer but, you know, you make the best of it."