Steven Whittaker gets lots of calls from hedge fund managers in search of people willing to sit on their boards of directors. “The pool is actually quite finite and small,” says Whittaker, a lawyer at London-based Simmons & Simmons and author of a how-to-be-a-director guide for the London-based Alternative Investment Management Association. He says he keeps a folder with about 45 names of willing directors, most of whom serve on more than one board and many of whom do so for a living. As the...