A massive majority has given Lib Dem councillor Lorna Dupre the seat as the new county councillor for the Sutton Ward.
She replaces Tory Cllr Phil Read who died before Christmas and had served the area for 40 years.
The by-election won Liberal Democrat Cllr Dupre 1,063 votes - more than the other three candidates put together.
Mike Bradley (Conservative) received 651 votes, Pete Bigsby (UKIP) 208 and Owen Winters (Independent) 102.
The county council is now made of up of 31 seats for the Tories, 14 for Lib Dems, 11 for UKIP, eight for Labour, four for Independents and one vacancy.
Cllr Read was a Tory county councillor who quit the Conservatives on East Cambs District Council over selection issues and disenchantment with the party nationally over the bedroom tax and HS2.
He died in December after a long illness.
A farmer, he was first elected to Cambridgeshire County Council in 1975.
He joined Sutton Parish Council in 1973 and was chairman from 1975 to 1977. He also joined East Cambridgeshire District Council in 1973 and served on the planning, environmental health, housing and finance and policy committees.
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