The seat in Corby in Northamptonshire was up for grabs Thursday because novelist Louise Mensch, who won a narrow victory in the 2010 general election, decided to join her husband, manager of Metallica and Red Hot Chili Peppers, in the United States. Andy Sawford, the Labor candidate, won by 7,700 votes, almost four times Mensch's margin of victory, The Financial Times reported.
Conservative Prime Minister David Cameron called the defeat a "classic mid-term result."
But Sawford and Labor leader Ed Miliband, who joined him in Corby, hailed the vote as a sign of things to come. Sawford said it was a "damning verdict on Cameron's betrayal of the British people."
The Liberal Democrat candidate came in fourth behind the United Kingdom Independence Party in another blow to the governing coalition.
In Manchester Central, where Labor candidate Lucy Powell replaced a Labor MP who ran for police commissioner, the Conservative candidate received less than 5 percent of the vote. The Liberal Democrat share of the vote dropped sharply, the Times said.
Stephen Doughty won in Cardiff South and Penarth, keeping the Welsh district in the Labor fold.
The one Labor defeat Thursday was in Bristol, where an independent won the mayoral race.