The Brits seem to love their laugh tracks. The laugh track is slowly dying in the US, but I'm having a hard time thinking of a British comedy show that doesn't use it. Of course, my access to them is limited since I'm on the wrong side of the Atlantic, but still.
It's always weird to hear laughter in Mitchell and Webb since a lot of the sketches are obviously shot in multiple locations, so there couldn't possibly be a studio audience watching the whole thing.
Much like Hugh Laurie had to wait to play a drug-addled, crime-solving doctor to make it into the American market, there is a serial killer in Robert Webb's future. He was born to play a sinister weirdo.