This is a very odd pair of episodes, "What the Butler Saw" being essentially a very British comedy and "The House That Jack Built" an intense sci-fi melodrama.
"Butler" is a deliberately more comedic re-telling of an earlier Honor Blackman story, in which very faithful military men appear to be leaking important state secrets. To get to the bottom of it, Emma becomes the seducer of a ladies' man, and Steed first impersonates top-ranking members of each armed service and then turns to butlering to keep a close eye on the suspects. The humor is English farce, not so amusing to American audiences. Probably the funniest thing in the episode is Steed's variety of facial hair disguises while cozying up to the Army, Navy, and Air Force officers. There's also a fairly amusing chase in the finale, with Emma pursued through a series of opening and shutting doors, one after another, all in a straight line and only a few feet apart from each other.
"House" is the better piece of the two, an often genuinely creepy and very atmospheric haunted house story of another color. A nonexistent dead uncle bequeathes Emma his house in the country - which turns out to be an eerie automated prison, designed to become her tomb by a madman with a grudge. Two things especially stand out in this one: the surrealistic sets of the mechanized haunted house, which are really unsettling, and Diana Rigg's virtual one-woman performance as the mouse caught in the trap.