David Butler, who has died aged 98, taught the British to understand elections. He was not the first to try, but he was much the most successful and influential, notably on BBC TV election night coverage from 1950 to 1979, and then on the radio and in the press until 2010.
He did not invent the term psephology (from the Greek word psephos meaning a pebble, since the Greeks used pebbles to vote), but he put it into the language. He did not invent the concept of a “swing” – the shorthand way of expressing the relationship between a party’s performance and that of its rivals – but he popularised it and made it the basis of all subsequent electoral analysis. He did not invent, only rediscovered, the cube law – the formula used to translate a given share of the vote in a first-past-the-post election into the likely number of seats that each party would win – but he brought it into general use.
