In answer to the question, is the bottom about to fall out of the contemporary art market, Richard Feigen, the 77-year-old veteran New York art dealer, a man who has spent most of his professional life handling Picassos, Van Goghs and Beckmans – a man of formidable reputation and immaculate taste, a man with an eye – tells the story of how he was almost trampled in the mud by the occupants of a platoon of shiny BMWs in London last year.