Sarah Dyke, the new Lib Dem MP for Somerton and Frome, won 21,187 votes, more than twice the 10,179 received by the Tory candidate Faye Purbrick following the resignation of the former Conservative MP David Warburton.

This saw a 30 point swing away from the Conservatives in the constituency, with the Liberal Democrats confident of victory from early in the evening.

While Labour and the Tories attempted to manage expectations, the Lib Dems were jubilant.

A Liberal Democrats poster at the Bath & West Showground in Shepton Mallet, Somerset, as counting begins in the Somerton and Frome by-election, called following the resignation of David Warburton amid allegations of sexual harassment and cocaine use. Picture date: Thursday July 20, 2023. PA Photo. See PA story POLITICS ByElections. Photo credit should read: Ben Birchall/PA Wire

A Lib Dem spokesman said: “We’ve not just won, we’ve romped home in Somerton and Frome.

“The Conservative vote is in freefall.”

Party leader Sir Ed Davey joked: “I think we’re going to need a bigger tractor.”

Rishi Sunak avoided becoming the first prime minister since 1968 to lose three by-elections on the same day as Labour failed to secure victory in Uxbridge.

Lib Dems overturn large Tory majority to make inroads in former heartlands