In a small, windowless room away from the crowds at the Barcelona foundation built to maintain the legacy of Joan Miró there is his library. It contains poetry, of course, as well as Plutarch, Hemingway and Lewis Carroll. But on the same shelves there are other books – the pulp fiction thrillers of Edgar Wallace; the schlocky master criminal Fantômas novels; a David Lodge; an unread Ulysses.

It says a lot. For such a wildly imaginative, radical artist there is lots that is reassuringly everyday about Miro. He had a very happy, stable marriage. He was extremely organised. He wasn't known as a big drinker or party animal. In photographs he has no Picasso or Dali-like swagger. He looks like a slightly apprehensive accountant, worried that he's mislaid some receipts.

But it is his art that makes Miró the titan that he is. Next month Tate Modern in London will stage the first major UK exhibition devoted to his work for nearly 50 years – a remarkable gap which, Tate hopes, will mean an entirely new generation can have their eyes opened to one of the most important of all 20th century artists.

The show, which will travel to Barcelona and Washington, also aims to confound expectations and explode a few myths. "Miró's work is often understood in ways that are a little simplistic," conceded the show's co-curator, Marko Daniel. "People look at his work as if it were childlike, or childish, and they tend not to see the depth of passion that goes into it."

Today Miró, a genuine pioneer and forefather of abstract expressionist art, is revered in Spain. Not as a hero necessarily but as a great man whose presence in his home city of Barcelona is everywhere.

It was not always the case. During most of the Franco years Miró was better known abroad. "He went from being almost entirely invisible in the Spanish art world to being feted as the greatest living painter in Spain," said Daniel.