Liz Truss Brought Libertarians to Power in the U.K. and Quickly Out Again

LONDON—A few days after Liz Truss first was elected to Britain’s Parliament in 2010, she visited the Institute of Economic Affairs, a libertarian think tank in a cramped Georgian house a stone’s throw from Parliament in central London.

There she met an old college friend, Mark Littlewood, director general of the IEA, and pitched an idea. “Mark, we are going to set up a caucus of free-market MPs,” Mr. Littlewood recalls her saying.

It…