A Jewish councillor has quit Hackney's ruling Labour party and joined the previously all-Charedi Conservative opposition.
Linda Kelly, a former speaker of the north London council, was elected in 2002. She fell out with Labour after protesting at its planned budget cuts.
"I made a stand on behalf of my constituents," she said. "They expect councillors to speak up and fight for them. But dissent in the ranks can't be accepted."
The defection of Councillor Kelly - a member of the local Gan Eden Indian Jewish community - increases the Conservative representation on the 58-member council to five. There are three Liberal Democrats, two of whom are also Charedi.
But while a few Jewish councillors remain on the dominant Labour group, none hail from the large strictly Orthodox community.
Tory group leader Councillor Simcha Steinberger said Mrs Kelly was "one of the most hard-working councillors. If there was one councillor you'd want in your party, I'd choose Linda Kelly."
She joined her new colleagues in a meeting with Communities Secretary Eric Pickles to discuss his Localism Bill, designed to give communities greater say over planning and other issues.