For several years now, one of the joys of the Williamstown Theatre Festival has been the revivals of obscure, but cherishable British plays of the 1960's and 70's, David Storey's Home, for example or Simon Gray's Quartermaine's Terms, to name two examples. Bernard Pomerance's The Elephant Man is a late (1979) product of the period, even if it is by no means obscure today, thanks mostly to David Lynch's remarkable film (1980), and even if it was written by an American.