Elton John launched the final concert at Britain's legendary Glastonbury Festival on Sunday, bringing down the curtain on the annual spectacular with what could be his final UK performance.

"I never thought I'd ever play Glastonbury," he told the crowd.

"It's a very special and emotional night for me – it might be my very last show in England, in Great Britain, so I'd better play well and entertain you."

The 76-year-old pop superstar is winding down a glittering live career with a global farewell tour, having played his last concerts in the United States in May ahead of a final gig in Stockholm on July 8.

Glastonbury, Britain's best-known music festival, has been hosted on a farm in southwest England for five decades. John took to the main Pyramid Stage on Sunday night.

"Elton's a legend," PhD student Giles Briscoe, 26, said as he headed to the stage hours ahead of the set, wearing a replica of the baseball outfit John famously wore at his famous 1975 concerts at Dodgers Stadium in Los Angeles.

"The fact that he's going to perform on such a big stage, at such a historic moment of his career, is such a big event."

John's husband David Furnish revealed that the four different guests would feature on stage, promising the show would differ from the global icon's sets on his marathon Farewell Yellow Brick Road tour over recent years.

"This one is very special. It is not just another day in the office," Furnish told Sky News.

He also revealed that John would not stop making music after the tour ends next month, and would start work on a new studio album later this year.

John's UK swansong caps days of big-name performances in front of more than 200,000 fans at Glastonbury, including veteran US rockers Guns N'Roses, who were making their debut at the long-running festival in the coveted Saturday night headline slot. (AFP)