Oh God. Watching Gosford Park is a lot like watching a car crash. Not that it’s a bad movie (though the swirl of inter-related characters at the start is a tad confusing); it’s a fascinating study of the utterly ugly, alien, repressed, hypocritical, upstairs / downstairs world of the British class system. Offensive, odious, awful.
Gosford Park itself is played by Syon House, just outside London. You’ve seen it in just about every other Britlit period drama from The Golden Bowl to The Madness of King George.