Nisbet told the Dundee conference of the Association of Educational Advisers in Scotland (traditional name preserved, but it doesn't trip off the tongue) that Tom the cat had the right idea.
Plagued by Tom's nightly excursions to the rooftop to screech and howl with his mates, his owner thrice warned him to mend his ways. But there was no quality improvement and there was only one thing for it - a trip to the vet's for the snip.
Returning home, he thought Tom might welcome a convalescent night in, but the cat slipped out and was back on the roof causing havoc. The exasperated owner shouted up: "Tom, come down, you know you can't do anything now."