Americans are beginning to obsess about decline, but the British long ago turned brooding over fallen empire into an art form.

“The Hour,” a BBC America series starting on Wednesday, is among the best of the genre. It’s a six-part thriller that blends the Suez crisis, one of Britain’s sharpest intimations of loss, with a more intimate look at sex, ambition and espionage in the workplace.

Any period piece set in the 1950s is bound to look a lot like “Mad Men,” and this narrative also unfolds through an amber haze of cigarette smoke, whiskey and social taboos. Yet unlike the many sterile “Mad Men” knockoffs that American networks are bringing out in the fall, like “The Playboy Club” and “Pan Am,” this BBC series isn’t a pale imitation of anything else on television. “The Hour” does borrow from the movie “Broadcast News,” as well as the 2003 BBC mini-series “State of Play,” but with a style and intelligence all its own.

The series opens in the offices of the British Broadcasting Corporation in 1956, only five years after the first Cambridge spies were unmasked as double agents, and just as President Gamal Abdel Nasser is consolidating power in Egypt. It’s a time of unsettling change, except at the BBC, where even driven reporters are assigned to do feel-good newsreels about debutante balls and royal visits.