Terminal for Labour and for Gordon Brown. That has been the predictable tenor of the headlines covering Labour's disaster in the Crewe and Nantwich by-election.

But history offers no warrant for such a reaction. Until 1997, it was quite normal for governments to lose by-elections. Between 1922 and 1997, governments won just four by-elections from opposition parties and lost no fewer than 126. In 1962, the Conservatives famously lost Orpington to the Liberals on a swing which, if repeated across the country, would have left them with just one seat, South Kensington. Yet they came within a hairs-breadth of winning the 1964 general election, just two and a half years later. On a single day in 1968, Harold Wilson's Labour government lost three by-elections on swings of 15 per cent, 18 per cent and 21 per cent. Yet it entered the 1970 election as odds-on favourite.