Thanks Steve.
This is something which has puzzled me since I first read about it, as the plumbing methods commonly used in the U.K. are rather different (not to mention very antiquated!). I saw the pipework when I was in the U.S., but never really traced it that closely.
I'm trying to visualize this "wet venting" system. Would this be something along the lines of taking a pipe upward from a fixture on the first floor and using that as the actual drain line for a second-floor appliance?
So there would then be a vent pipe from the second-floor trap, but the first-floor appliance effectively uses the drain from the second-floor appliance as its vent?
