Who scares wins. That has been the motto of many, often successful Conservative election campaigns. Fear may not be an edifying strategy for securing power, but the Tories have repeatedly demonstrated that it can be highly effective. Time and again, they have persuaded voters that Labour is just too risky to be trusted with government. The “red scare” of 1924, whipped up with the aid of the fraudulent Zinoviev letter, brought an abrupt end to the short life of the first Labour government. The “tax bombshells” dropped on Neil Kinnock in 1992 exploded his dreams of becoming prime minister. Tory...