"It's good to have an enemy," says George Birnbaum, one of the godfathers of modern populism. "Very rarely will you find someone who's loved by everybody." A political consultant for 30 years, he helped Benjamin Netanyahu come to power in a surprise victory in Israel in 1996, and Hungary's Viktor Orban in 2010. He has clients in many countries, and flits nowadays between New York, Dubai and Harare. George Birnbaum built his reputation as one of "Arthur's kids" - under mentor and late business partner Arthur Finkelstein, a brilliant mathematician who re-invented the art of political campaigning in the US,...