On a chilly day outside the White House, tourists milled about, Secret Service agents stood guard and a group of protesters held aloft a banner that demanded: “Over 14,850 Palestinians killed, how many more before a ceasefire?” Among activists embarking on a five-day hunger strike is a face instantly recognisable to fans of TV series such as Sex and the City and The Gilded Age. Cynthia Nixon is following in a long tradition of actors using their platform to further a Washington cause. But she is also stepping into a Hollywood rift. While the entertainment industry has shown remarkable unity...