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When politicians have periodically to meet their maker -- the electorate -- they panic. This week's apparent rogue poll suggesting Gordon Brown might remain in Downing Street after the election has led some Tories to question the existence of God. Could it be true? David Cameron was the future, once. Is the great black thundercloud of Downing Street about to obliterate him?

First some history. These wobbles happen in most elections. There have been few more unpopular governments than Callaghan's in 1977. Two years ahead of the 1979 election, the Tories under Margaret Thatcher were 20 points ahead. Yet Labour contrived to edge ahead in late 1978, when the nation was facing industrial meltdown.

Thatcher recovered and went into the long election campaign that began in March...