Labour retained a parliamentary seat in west London in Thursday's by-election, with an eight percent swing from the Conservatives, though turnout was the lowest in more than a decade.
Seema Malhotra held Feltham and Heston for Labour with more than 12,600 votes, 54 percent of the overall vote and 6,203 votes ahead of her closest rival, Conservative party candidate Mark Bowen.
Turnout was 28.8 percent, the lowest for a by-election in eleven years and thirty percentage points below the figure for the last general election in May 2010.
This result is a great victory for Labour which shows the progress we are making under Ed Miliband's leadership, a vote of confidence in the way Labour is changing, listening hard, winning back the trust of the people we seek to serve, Malhotra said after the result was announced.
This is also a wake-up call for (Prime Minister) David Cameron. This result shows how this Tory-led government is totally out of touch, she said.
The by-election followed the death of Labour MP Alan Keen last month. Keen took 43.6 percent of the vote in the May 2010 general election, 12 percent more than his Conservative rival.
The by-election was held at a time when the Conservative-Liberal Democrat ruling coalition is pushing through severe austerity measures, leading to rising unemployment, to reduce the large deficit.
The Lib Dem candidate Roger Crouch won just six percent of the votes, down eight percentage points from the 2010 election, reflecting the party's waning popularity as a junior coalition partner forced to compromise on some of its principles.
There had been limited public enthusiasm for the poll, coming just 10 days before Christmas in an area close to London's main Heathrow airport, the largest local employer.
Opinion polls this week showed the Conservatives had overtaken Labour in the country as a whole, with Cameron enjoying a bounce after he vetoed a new European Union treaty because he could not get guarantees of protection for the important financial sector.
Since losing power 18 months ago, Labour has been struggling to regroup under new leader Ed Miliband, whose critics say he has yet to win the broad support the centre-left party needs to challenge the coalition.
The government has a working majority of more than 80.
(Reporting by Stephen Mangan; Editing by Tim Pearce)