An oddity of theatrical posterity is that a dramatist’s most famous play is often overtaken in the reputation stakes by what once seemed a lesser text. Many judges would now give the top spot in the Tom Stoppard canon to Arcadia rather than the more fabled Rosencrantz and Guildenstern are Dead, while Edward Albee’s A Delicate Balance  is widely considered ­superior to his long-time blockbuster Who’s Afraid of Virginia Woolf? and Arthur Miller’s Death of a Salesman, the play name-checked most often in his 2005 obituaries, is now ­routinely beaten in polls of the greatest dramas by his own The Crucible.Six and a half decades ago, the dramatist saw the Salem witch trials in seventeenth-century Massachusetts – in which a group of young women accused