Peter Lewis, the philanthropist and art collector, has always been something of an iconoclast. So some of his friends and colleagues were not surprised by his decision to leave the board of the Guggenheim Museum abruptly and stop handing over cheques to the New York institution.

A billionaire, Lewis made his money selling auto insurance in Cleveland, Ohio, having inherited a small company called Progressive Mutual from his father. Over the years, he transformed Progressive from a sleepy company into the third-biggest insurer in the US.