He is, perhaps, thinking of the winter solstice.
There is, or was, much logic in changing the clocks, because of the asymmetric way in which the times of sunrise and sunset change relative to midday as the seasons progress. In the days when most labour took place out of doors and depended on natural light, this made sense.
Nowadays, perhaps, we should stick to one time throughout the year. Would it be impossible for those people whose work does depend on daylight to shift their hours of work rather than impose a change on everyone else's clock?