Jean Dubuffet’s ‘Tapié grand-duc’ has little in common with the classical portrait. He sketched his art-critic friend Michel Tapié with just a few lines. The small eyes are closely spaced in the large, deformed head. The pasty mixture of oil paint and plaster creates a striking sense of plasticity. The work reveals a preoccupation with Art Brut, the art of the mentally ill, whose primitive, anti-academic aesthetic Dubuffet admired. He took painting and portraiture back to a raw state and produced an image as full of violence and destruction as it is of humour and irony.