It seems a bit pointless when they could do so much for safety by potting black BMWs alone. I would guess that this started as a joke. Individual police officers have a wicked sense of humour, especially when asked silly questions. How many cars did Mr Emslie think an officer could deal with at the same time.
Course its true - nobody ever heard of the sociological perspective of 'canteen culture'. 'Course, the ratinalle behind the snooker would most probably be subliminal. You should read a book called "Bent Coppers" - some very interesting and true shannanigans!