Those of our self-appointed moral guardians who fulminate against violent and sexual excess in contemporary screen dramas have presumably either never seen a Jacobean tragedy onstage or chosen to ignore that the aforementioned strains are part of a long and, so to speak, honourable cultural tradition. John Webster's The White Devil contains the usual crop of murderous infidelities and political intrigues and, in Gale Edwards's fine production for the RSC (whose Stratford opening David Murray rightly admired in these pages last April), a light sprinkling of incest to boot.