Joan Miro may be most often thought of as a painter of mysterious dreamscapes and surreal imagined landscapes. But a blockbuster exhibition at Tate Modern — the first survey of the artist's work since 1964 -will show him as a committed critic of the nationalist regime in Spain. Joan Miro: the Ladder of Escape, which opens in April, will bring together what its co-curator Matthew Gale described as “150 just fabulous paintings”.