Agent Running in the FieldBy: John le Carr 'The British spy thriller at its unputdownable best' Observer SELECTED FOR BBC 2 BETWEEN THE COVERS ________________________________ Nat, a veteran of Britain's Secret Intelligence Service, thinks his years as an agent runner are over. But MI6 have other plans. To tackle the growing threat from Moscow Centre, Nat is put in charge of The Haven, a defunct substation of London General with a rag tag band of spies. His weekly badminton