Glastonbury's greatest secret sets of all time – and the favourites to surprise fans this year

• Over the years, artists including The Killers, The Libertines, Lady Gaga, Foals and Franz Ferdinand have also popped up "unannounced" at Glastonbury. Last year, an act supposedly called The Churnups, conspicuous by their late-evening Pyramid Stage slot despite being an unknown entity, turned out to be The Foo Fighters. The festival is famous for its secret sets, surprise guests and big names appearing in unexpected places, so while Dua Lipa, Coldplay and SZA headline this year, it is the TBA slots that may well provide some of the most memorable moments.