A wicker basket spills roses across a dark table: cream, blush pink, a single bruised crimson bloom near the top, and a few petals already fallen to the ledge below. It is a 19th-century still life, the kind that hangs quietly in a museum, and in 1983 it became the face of New Order's second album, Power, Corruption & Lies.

Peter Saville set an oil painting of flowers, A Basket of Roses, in front of a synthesiser-driven record, with no band name and no title anywhere on the UK sleeve. In the upper right corner, a small grid of coloured squares interrupts the romance: a private code, wordless, that seems to belong to another century than the flowers.

The mismatch is the whole point, though the sleeve refuses to explain itself at a glance. What that grid of colours actually spells, where the painting came from, and how a small independent label persuaded a national museum to lend its property to a pop group are all questions hiding behind the roses.