UK's Brown faces leadership challenge after Labour's thumping by-election defeat

However, the Conservatives feel that the result mark the "end of New Labour."

Conservative leader David Cameron has hailed the Crewe and Nantwich by-election win a "remarkable victory" and said it marked the "end of New Labour."

However, "there won't be one hint of triumphalism or one hint of complacency" from them, Cameron said.

"We don't want to win just because Labour is failing. We don't want to win just because the Prime Minister is failing. We want to win because we have the right ideas for Britain's future," he said.

Sniffing a return to power at the next general election, Cameron said he would put together a "broad coalition" to defeat the Labour Party.

"Just like in the local elections, just like in the London mayoralty election, thousands of people came to vote for the Conservative Party for the first time and my message to those people is 'We will not let you down'," Cameron said, following news of Labour's defeat.