The arena fills with their harmonies, each aspect of every song a crucial element in the band’s equilibrium (Getty) Four decades after five boys formed a group at school to play music together, over 20,000 people gather in the O2 Arena on a Friday night to watch them perform, as they have in venues across the world, over the last 40 years. Tickets for this tour sold out in minutes. Millions of records sold. Charts topped with critically acclaimed albums.