The revolt of the working class against the center-right/center-left establishment is the biggest political story of the past decade. For the most part, the working class has moved right rather than left, fueling the growth of conservative populism throughout the West.

Last week’s U.K. general election underscores this shift. As an analysis by the Financial Times shows, there was a strong correlation between a district’s share of working-class voters and the swing toward the Conservative Party. In seats with high shares of...