The scratchy, inky anarchy of Quentin Blake’s unmistakable illustrations

This week sees the opening of the £12.5m Quentin Blake Centre of Illustration, a 20-year project that will house the artist’s archive and champion the art of drawing. From his ‘odd couple’ pairing with Roald Dahl to his own books, the 93-year-old has been a prolific, joyful presence in millions of childhoods. Patrick Smith unpacks his appeal