The broadcaster and naturalist introduced a four-minute prequel video to the huge crowds gathered ahead of Kylie Minogue's performance at the festival, being held on Worthy Farm.

The extended trailer features a new song, Out There, from Australian singer Sia, who collaborated with composer Hans Zimmer on the track.

Sir David praised the festival after Glastonbury banned the sale of water, soft drinks and alcohol in plastic bottles this year. In 2017, the last time the event was held, more than 1 million single-used plastic bottles were sold on site.

Festivals goers were encouraged to bring their own bottles or buy steel flasks that could be filled with water at taps and water kiosks around the site.

The broadcaster's Blue Planet II documentary, which has been shown in countries around the world, highlighted the dangers of plastic pollution to marine life and the 93-year-old said the move at the world's largest greenfield festival would have an impact.

"That is more than 1 million bottles of water that have not been drunk by you in plastic," he said to cheers and applause. "Thank you, thank you."

The song Out There has been inspired by Planet Earth II, the BBC's previous series also fronted by Sir David, and was composed by Sia, British songwriter Christopher Braide and Zimmer.

Sia said: "I was honoured to be asked to collaborate with Hans Zimmer for Seven Worlds, One Planet.

"The work this program - and the Planet Earth series - does on behalf of our planet is essential and I'm proud to be a part of it."

BBC Radio 1 debuted the full track in the UK at the same time as the prequel played out across screens at Glastonbury. The prequel was also simultaneously broadcast in almost 50 countries globally at the same time as it was shown to Glastonbury audiences.

Australian Associated Press