For more than two centuries, New York has been the most important centre of commerce in the US. Today 3.7m people work there, making it easily the nation’s greatest concentration of jobs. And they work hard: in 2006, according to the US commerce department, New York delivered $1,100bn of the nation’s $13,100bn gross domestic product.

But while the city’s place as the US business champion remains uncontested, workplaces there are seeing significant changes. “There is a shift under way in the social contract,” says Linda Barrington of the Conference Board, an organisation that studies business management.