Painter. Born the Netherlands. September 1938, avoiding the Nazis, he moved to Hampstead and, assisted by Ben Nicholson, rented a room in the house with the plaque. He painted it white, including all the cheap furniture. At this time Nicholson was living with Barbara Hepworth at 7, Mall Studios (behind Mondrian's house and off Tasker Road - they could see each other's windows). The 3 artists were friends and met and discussed their work frequently. At the outbreak of war Hepworth and Nicholson took their children to Cornwall, inviting Mondrian to go with them but he stayed in London and in September 1940 moved to Manhattan where he died.
He didn't just like straight lines - he suggested to Peggy Guggenheim that she should see Jackson Pollock's work, and the rest is art history.