IN the advertising business, where stability is as fleeting as a client's gratitude, change has been particularly rapid in recent years. Yet the men who run J. Walter Thompson, the world's largest agency, have held steadfastly to their time-tested policies. They successfully offered creditable advertising ("Pan Am makes the going great," "There's a Ford in your future"), a rich array of services, and a sturdy sense of security to an impressive roster of blue-chip clients. Today, however, the agency's once imperious élan has been badly shaken.
Last week Thompson disclosed that its third...