The U.K. Independence Party won a seat in the British Parliament for the first time on Friday, a significant breakthrough for the anti-immigration force and a protest vote against the country's mainstream parties.
The party also posted a strong — and unexpected — showing in another special election held in Heywood and Middleton in northern England.
UKIP candidate Douglas Carswell won the special election in the eastern England constituency of Clacton-on-Sea with 12,404 votes. The Conservatives' Giles Watling came in second with 8,709 votes.
In the other race, Labour's Liz McInnes beat UKIP's candidate by only 617 votes.
Turnout in the Heywood and Middleton contest was only 36 per cent. Low turnouts are one reason why byelections often produce surprising results that aren't necessarily repeated in general elections.
The contest will nonetheless send a chill through the political establishment in Britain, as it showed UKIP is now appealing to Labour voters as well as to disaffected members of the Conservative Party.
"There won't be a shred of complacency from us as we reach out to all of those voters who didn't vote Labour and didn't vote at all," Labour leader Ed Miliband said.
UKIP, which wants to curb immigration and pull Britain out of the European Union, has attracted growing numbers of voters. It took the largest share of British votes in May elections for the European Parliament.
Thursday's special election in Clacton was triggered when Carswell, who represented the area in southeastern England as a Conservative, defected to UKIP in August.
"The idea that we are somehow the Tory party in exile, that myth died," Carswell told Sky News. "We are a different party that stands for all Britain and all Britons, from disillusioned former Labour voters to people who have given up on politics altogether, every bit as much as for traditional Conservative voters."