The Conservatives have lost control of the southern Wokingham council to no overall control, after the Liberal Democrats won seats on the authority.
The loss of Wokingham — the home of the Conservative MP John Redwood — comes after Boris Johnson’s party suffered a string of defeats at the local elections.
The result in the town of Berkshire, England, will unnerve Tory strategists, with the party previously dominating the council over the last decade.
After all 18 seats were declared, the Liberal Democrats gained five councillors, toppling the Tory council into no overall control on Friday afternoon.
Daisy Cooper, the Lib Dem deputy leader, told The Independent: “This is another hammer blow to Boris Johnson’s Blue Wall which is now crumbling before his eyes.
“Lifelong Conservative voters have said enough is enough. This country is gripped by a cost of living crisis for which Boris Johnson’s out of touch Government has no answers.
“Conservative MPs like John Redwood in Wokingham need to start listening to their constituents who know the time is up on Boris Johnson as prime minister.”
It comes after Mr Johnson admitted the Conservatives had endured a “tough night” following historic defeats in London to Labour, including Wandsworth, a seat held since 1978, and Westminster — a Tory council since its creation in 1964.
Speaking to broadcasters, the prime minister referred to the local elections as “mid-term”, adding it was a “mixed-set of results”.
As of 1.30pm, the Conservatives had lost 168 council seats, while Labour had gained 41 and the Liberal Democrats had won 77, including town hall seats in David Cameron’s former backyard of West Oxfordshire.
In a message to activists earlier on Friday, Sir Ed Davey, the Lib Dem leader, claimed the results amounted to “an almighty shockwave that will bring this Conservative government tumbling down”.
“The tectonic plates of British politics are shifting beneath Boris Johnson’s feet. And now it’s time for Conservative MPs to plunge him into the abyss,” he added.
John Curtice, an elections expert, described the Lib Dem improvement as “relatively modest”, saying: “It’s up a couple of points as compared with 2018.”
The party had won more seats than Labour largely because of the technicality of gains “in smaller, more rural councils where the wards are smaller, so you get more seats per person”.