Twenty years ago, a 1939 poster printed by the British government with the words ‘Keep Calm and Carry On’ turned up in a second-hand bookshop in Northern England. And lo! A decor trend was born: teatowels, T-shirts, mugs, phone cases, condoms, and a zillion riffs on the phrase.

Bookshop owner Stuart Manley talks about unearthing the poster that spawned countless imitations; author Owen Hatherley explains why the poster was NOT, in fact, an exemplar of Blitz Spirit and British bulldog courage and whatnot; and psychologist and therapist Jane Gregory considers whether being told to keep calm can keep us calm.