Like the snow in Frozen, Let It Go is everywhere, and it’s not disappearing without a fight. It’s the main reason why the Frozen soundtrack has been the No 1 album in the US for nine weeks and counting – Beyoncé only managed three – and a significant reason why the film became the highest-grossing animated movie of all time. On YouTube, where it sits alongside countless amateur cover versions, spoofs, supercuts and fan-made videos, the Let It Go sequence uploaded by Disney last December has attracted almost 180m views. Still, these mind-boggling statistics strike me less forcefully than my daughter’s unprecedented obsession. To her, an older sister at an age where boys are beginning to become a source of intrigue rather than irritation, and conventional Disney princesses are a prissy drag, it’s more than a song. It’s a glimpse of the future, a vessel for secret knowledge.