'Howard Brenton is one of Britain''s best-known and most controversial dramatists. The Romans in Britain was the play that brought calls to bring back censorship when it was first staged at the National in 1980. It conjures up ''an era that is culturally as well as historically remote which is a notoriously difficult task, but Mr Brenton achieves it with great skill and effect...a very good play indeed''. In The Thirteenth Night- ''He sets the characters...