In September 1991, three socially-awkward slacker kids from Seattle changed the world. It’s genuinely difficult to overstate the impact Nirvana had – not just on music, but on popular culture as a whole – when their second album, Nevermind, dropped in the autumn of that year. Not since a certain Liverpudlian quartet had a phenomenon torn through the mainstream with such power; that bandleader Kurt Cobain had formed Nirvana with the idea of “mixing really heavy Black Sabbath with The Beatles” is no coincidence.