Professor Youngson delivered my first course in economics at nine in the morning in the David Hume Tower at the University of Edinburgh. I walked to his lectures in the dark. My student days coincided with a three-year experiment in which British Summer Time was extended to the whole year.

When I returned home, the news bulletins would regularly begin with reports of injuries to children: the carnage on Scottish roads was emptying its schools as it filled its hospitals. Only after a few months did data on road accidents become available, and the results were unequivocal: the number had fallen.

There were indeed more injuries in the darker mornings, but that was offset by a larger reduction in accidents in the lighter afternoons. “The whining schoolboy with his satchel and shining morning face” may go unwillingly to school, but Shakespeare was probably wrong to think he creeps like a snail. He hurries because he is late and is more likely to be injured on his dilatory journey home.