Even for the Lincoln Centre it was an unusual show, and an unscheduled one. Several hundred protesters turned up outside the arts complex on Manhattan's Upper West Side last week for the guerrilla screening of a short film. From a hotel on the other side of the street, a video was projected on to the centre's walls. The unwitting stars of the films were David and Charles Koch, the reclusive rightwing billionaire brothers whose secretive empire and network of influence and funding is emerging as a liberal rallying cause in America.

Director Robert Greenwald s opening gambit in what he pledges will be a year-long effort to publicize the Koch brothers political efforts drew about 500 protesters to Lincoln Center in New York last night, ending with an unauthorized 'rebranding' of the Center s David H. Koch Theater with the caption "I'm the Tea Party s wallet"