They are comedy sparring partners from Green Wing. Can the duo play stricken lovers in The Deep Blue Sea, the eviscerating play Rattigan poured his own heartbreak into? Warning: contains spoilers On 8 May 1956, Terence Rattigan stood outside the Royal Court theatre in London after the opening night of a revolutionary new drama. This was not one of his own plays but a sally from the upstart generation: John Osborne's …