Liberal Democrat David Siddans has been elected as councillor for the Rossett ward.
The victory in yesterday’s by-election marks a 25.6 per cent swing from the Conservatives, who were hoping to hold on to the seat left empty by the resignation of former councillor Michelle Woolley earlier this year.
The Conservatives were defending a majority of 1,412, but candidate Rebecca Burnett could muster just 704 votes.
The Lib Dems took the seat as Mr Siddans secured 48.9 per cent of the vote with 897 votes, up from 654 in 2011.
Turn out was 1,834, 38.3 per cent.
Coun Siddans believes his triumph was the result of his stance against Harrogate Borough Council (HBC) plans to develop housing at Cardale Park west.
He said: “The discussions of plans to develop the land at Cardale Park were certainly a big factor.
“Residents are agitated about it, and personally I feel they wanted to send a very clear message to the council.
“A good way of sending that message was to vote for me.”
He added: “I also live in the centre of the ward. The Cardale Park development is a big issue for me to get my teeth stuck into, and when I get my head around what has happened today, I will be able to sit down and work at it.”
Coun John Fox, Constituency Chairman, Harrogate and Knaresborough Liberal Democrats said: “This is the first Liberal Democrat gain from the Conservatives in the north of England this year. We are absolutely delighted to have overturned a huge Conservative majority. I think the people of Rossett were extremely concerned about the volume of development and how it could affect their property prices, and infrastructure, such as schools and community centres.”
Labour also suffered a drop, from 310 in 2011 to 106 for candidate Pat Foxall. This total was beaten by UKIP candidate Salvina Bashforth, with 127 votes.