Nostalgists often hark back to a “golden age” of TV drama, referring to the likes of ITV’s Brideshead Revisited, or the BBC’s I Claudius or The Forsyte Saga. This week on the South Bank, the BFI launches a season which examines a lost age of a different kind, that of the radical TV dramatists who scorched across British screens from the mid-Sixties, through the Seventies and the Margaret Thatcher era, and finally into the ambiguous world of New Labour.