Half a century ago, on 4 March 1970, an unexpected blizzard dumped more than 25cm of snow across central and south-east England overnight. Temperatures hovered around freezing and the snow settled, closing roads and airports. Morning trains from the Midlands arrived in London eight hours late.

The problem was the lack of warning. The Met Office did not start issuing snow alerts until the early hours, and most people were caught unprepared. While winter storms can be forecast, determining whether they will bring rain or snow requires precise modelling. A slight change in temperature can have a big impact on what form the precipitation takes.

Questions were asked in parliament about the snowfall. John Ellis, for the governing Labour party, was optimistic that the Met Office’s powerful new IBM computer might help predict such events in future.

The Conservative MP Nigel Birch was dismissive: “He [Ellis] said that he wanted to know when the weather was about to be out of the ordinary. My experience of British weather is that it is always out of the ordinary, and it will take more than a dozen computers to alter that.”

However, as the last 50 years have shown, better computers do improve weather forecasting, and we are now less likely to be surprised by unseasonal blizzards.