* Veteran rockers headline at sunny Glastonbury
* Mick Jagger, 70 soon, has no plans to quit
* Billy Bragg and Elvis Costello among day's lineup (Recasts with new quotes throughout)
By Belinda Goldsmith
PILTON, England, June 29 The Rolling Stones were gearing up for their debut performance at the Glastonbury music festival on Saturday, 50 years after starting out in the music business.
More than 150,000 revellers descended on the festival in rural southwest England for a bill topped by a band still pulling in crowds despite an average age of 69.
Organisers were carefully guarding details of the band's playlist for a set due to last over two hours.
Michael Eavis, who started Glastonbury as a gathering of 1,500 hippies on his farm in 1970, has publicly delighted in finally persuading the Rolling Stones to play.
"I'm looking forward to it because it is an iconic gig and it's an iconic band," guitarist Keith Richards told BBC's Radio 1. "Finally the two meet at last."
The Stones have already toured North America this year and will play several sell-out concerts in Britain this summer.
Frontman Mick Jagger, who turns 70 next month, said the once-controversial band still had something new to say, even if its voice seemed tamer now.
He said the Rolling Stones actually never set out to make waves in the 1960s, when newspapers were full of their drug use and love tangles and the band were accused of fuelling social unrest and falling moral standards.
STONES ROLL ON
"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.
"We were sort of sidetracked into this social thing by the mood of the times and ... the times themselves, which were galloping on."
Asked if his hyperactive stage performance tired him now that he was going on 70, Jagger said: "Occasionally." But he said he would go on performing as long as audiences wanted him.
Revellers at Glastonbury, which now attracts an older crowd with an average age of 36, enjoyed a warm, sunny day ahead of the main act of the festival, which started on Thursday in rain.
"Even if you don't particularly like the band, I reckon the music will get you going. I don't know how they do it at their age," said Sandra Guest, a care worker aged in her late 40s who left her two teenage children at home to attend the festival.
Some music fans planned to take advantage of the big draw of the night to watch some of the other acts in greater comfort.
"Hopefully everyone is going to be at the Stones and I will get a good spot to see Chase and Status, but I think my dad will be disappointed," said Dawn Furr, 31, a mental health support worker from Manchester in northern England.
Saturday's line-up also included Billy Bragg, Elvis Costello, Primal Scream and Noah and the Whale.
With 2,000 acts on 58 stages at Glastonbury, some of this year's more surprising inclusions are U.S. country music star Kenny Rogers and octogenarian British TV presenter Bruce Forsyth. (Additional reporting by Isla Binnie; Editing by Kevin Liffey)