A great puff of ugly black smoke was rising on the skyline as we drove up Route One from Saigon one overcast day in June 1972. North Vietnam’s Easter offensive was raging. I had picked up the car, driven by a driver I trusted, outside the venerable Continental Hotel. A Brit, Willy Shawcross, later the author of books on the war and much else, and his girlfriend were in the back seat.