When Ben Nicholson invited his Dutch mentor to live in London, it kicked off an intense artistic dialogue. Now a new exhibition explores their shared concerns and the way their paths divergedWhere were the paparazzi in September 1938? They should have been thick on the ground outside 60 Parkhill Road in Hampstead, for that month one of the 20th century's most audacious painters, Piet Mondrian, moved in. His arrival in England followed that of other leading avant garde artists, designers and architects, many of them having fled fascist or Soviet autocracies. For a brief period in the second half of the 1930s, London, or more accurately Hampstead and Belsize Park, became the focus for international modernism. Mondrian's presence in London, ...