Paul McCartney has cast doubt on his chances of headlining the re-arranged Glastonbury Festival next year.This year’s Glastonbury was cancelled due to the coronavirus pandemic, and while the festival is aiming to make a return in 2021, organiser Emily Eavis admitted earlier this week that she and her team are “quite a long way” from being able to confirm that its 2021 edition will go ahead as planned.Speaking to The Sun on the eve of the release of his new solo album ‘McCartney III’, McCartney said that he was eager to get back on the live stage “whenever I can” before bringing up the prospect of Glastonbury, which he had been set to headline in the summer.“People have started to find ways [of live performing] with Zoom and with socially.