“Grateful but unhappy”: writer Annette Kolb’s response to exile in America during the second world war summed up the feeling of most artistic refugees from Nazism. A famous photograph shows 14 of them at Pierre Matisse’s 1942 Artists in Exile exhibition: Mondrian, Chagall, Breton, Max Ernst, all look ill at ease, out of place. But in the front row on the far left – where else? – sits the stocky, pugnacious figure of communist artist Fernand Léger, for whom New York was “the most beautiful spectacle in the world”.

While his European peers flailed or withered in America, Léger arrived, went to a swimming pool and ... “What did I see? There were no longer [as in France] five or six divers, there were 200 at once. You no longer knew who this head, this leg, or this arm belonged to. You couldn’t distinguish them any more. So I jumbled up the limbs in my paintings and realised that this way I was much more honest than Michelangelo, when he concerned himself with every single muscle.” Thus the swimmers, brightly coloured with dark contours, float through “The Big Black Divers” and many other 1940s “plongeurs” paintings, their bodies advancing and receding, shifting contours and planes suggesting dizzying space, a “ballet mécanique” of interlocked silhouettes.