The Conservative party was “wiped out in its former London heartlands” on Friday after the last Tory seat on Richmond council was lost in a by-election.
The Liberal Democrats took the Hampton North ward seat from the Tories and held another in Teddington in votes on Thursday.
The town hall called the by-elections following the deaths of Conservative councillor Geoffrey Samuel, 92, and Lib Dem Martin Elengorn, 79, in November.
Both had sat on Richmond council for decades and Mr Samuel was believed to be the the oldest serving councillor in the UK when he died.
Twickenham MP Munira Wilson said: “The Conservative party has now been wiped out in their former London heartland after years of taking voters for granted.
"Local people are fed up of the Conservatives in both Westminster and Town Halls.
“Lifelong Conservatives told me Rishi Sunak is no better than the last failed Conservative Prime Ministers, and they want an end to years of sleaze and chaos.
"In swathes of London it is a two horse race between out of touch Conservatives or hard working Liberal Democrats "
At the local elections in 2022, the Conservatives suffered their worst ever result in the borough, losing all but Mr Samuel's Hampton North seat. The party had previously run the council with strong majorities between 2010 and 2018.
However, the Tories were on Friday celebrating a win in Hackney.
Conservative Ian Sharer, a popular local campaigner who has previously stood as a Lib Dem, gained the Cazenove Ward seat from Labour, winning 53 per cent of the vote.
It came after support for Labour candidate Laura Pascal collapsed in the east London borough.
Days before the poll Ms Pascal was suspended by her party and members were told to cease campaigning for her following allegations of transphobia and racism.
Posters showing a tweet she had liked, which suggested a trans woman was wearing "womanface" and it was comparable to blackface makeup, had been plastered up across the borough.
Her suspension was lifted on Wednesday afternoon, just hours before the by-election.
A source close Ms Pascal's campaign said :“It was totally impossible for Labour to snatch a win in a marginal ward with a candidate who embroiled herself in a racism scandal.
"Clearly the people of Hackney were deeply offended by this image of blackface to make some sort of clumsy and misguided comparison, which was flyposted all over the ward this week.”
But Labour did achieve a landslide victory in a Wandsworth by-election.
Candidate Sean Lawless held the Tooting Broadway seat for the party with almost 70 per cent of the vote. It came after Tory contender Otto Jacobsson was criticised for encouraging people to “go on strike” and not vote in his election leaflets.
