No one seems to know the answer. Children were happy this week to be given an extension to their holidays. They may have been puzzled why it took a week after the thaw for schools to be declared unfit for occupation, but they were not complaining. Many of the parents who had to make immediate arrangements for their care were less sympathetic to the authorities. Does no one go into a school during the holidays even when there is risk of frozen pipes, or for that matter even when tales of domestic disasters should prompt inquiry into the state of empty school buildings?

Other countries regularly experience winters far worse than even our exceptional one. Experts from Canada and Sweden described for the media the way they prevent mains pipes bursting through burying them deeper than we do. But for schools the problem lies indoors, or at least along the walls, not in the mains system. There is no explanation why empty public buildings elsewhere in the world do not pour with water.

A run of mild winters has made people blase. That may explain why householders failed to lag pipes, or if they were away did not drain tanks or maintain a level of heating. But surely in schools and other public buildings which shut down every year for a couple of weeks there are instructions applied regardless of the immediate weather forecast. Or have janitors been told that keeping costs down is paramount and prayer is the only weapon against the elements?

Human lapses would not matter if buildings were made to withstand our winters. If a school is put up in the Western Isles, it has to be of a design to keep out gale-driven rain. If it is being built in, say, Ellon it will face lower temperatures than in Exeter. These basic facts were well known to our ancestors. In an age of fiddly building regulations, they appear to have been forgotten. Delayed lessons and decamped classes testify to the shortcomings of modern design and technology.