I opened the train door window and stuck my head out and got a big schnozzful of evening. When I pulled my head in to avoid having it thunked senseless by an approaching pole, I looked behind and saw a man hanging out the next window, doing the same thing, grinning, not intending to be inconvenienced by a mere lethal hazard.
Overheard in the shirt shop: It would irritate my neck. I can't be expected to go about with an irritated neck all day, just because of rules.
In Cambridge they apparently let the cows frolic and feed on the city centre grass, once in a while, or regularly, but maybe not every day. Which explains the wafts of dung, and the trampled rats, and the hoofprints on the cars.