This is an extraordinary story. In 1845 John Snare, an unremarkable Reading bookseller, goes to an auction in a defunct boarding school where he buys, for £8, a painting catalogued as a half-length portrait of Charles I, ‘supposed’ to be by Van Dyck. In mid-19th century Britain a Van Dyck is a known and immensely desirable object, but from the outset Snare thinks that he has found a painting by Diego Velázquez, whose work is, by comparison, little known at the time here.