Glastonbury, 2009. Fleet Foxes, the Seattle folk-rock band whose recently released debut had just become a word-of-mouth hit, took to the Pyramid stage before more than 100,000 people and quickly wondered what the hell they were doing there.

“It’s a pleasure to be terrified by you,” said the singer Robin Pecknold, while his childhood friend Skyler Skjelset, the band’s guitarist, had the dazed look of a man dreaming he was on stage at the world’s biggest festival without knowing how or why. Thousands in the crowd were singing along to White Winter Hymnal and Oliver James, beautifully church-like but distinctly uncommercial songs inspired by a trip to the Lake District that Pecknold went on when he was 19 and the Steeleye Span records he