Stephen Doughty will be the new MP. He's increased Labour's majority slightly, but turnout was just 25%.
Counting begins to find out who voters in Wales' biggest constituency by population have chosen as their new MP.
It's the final day of campaigning before the Cardiff South and Penarth by-election.
Shadow Welsh Secretary Owen Smith MP has hailed Labour's win in the Cardiff South & Penarth by-election as a sign voters want "a new deal".
– Owen Smith MP, Shadow Welsh Secretary
Voters in Cardiff South and Penarth have sent David Cameron a clear message today: they want a new deal in this country - a One Nation deal which delivers a fairer society and an economy that works for us all not just the most privileged.
People here rejected the Conservatives mean and divisive idea of 'sink or swim' Britain and urged Labour instead to build a country and an economy in which everyone might have a fair chance, a country we can be proud of once more.
The leader of the Opposition in the Assembly has congratulated his party's candidate in the Cardiff South and Penarth by-election. Andrew RT Davies says the second-place won by Craig Williams shows the Welsh Conservatives have 'the action and ambition to achieve for Wales.'
Craig fought a determined campaign and I congratulate him on retaining second place – ahead of both the Welsh Liberal Democrats and Plaid Cymru.
This is a successful result that continues to show we are the only real opposition in Wales.
13 years of lazy Labour-led Welsh Governments have left Wales the poorest part of the UK – and still they lack the ambition to get us back on track.
Their second-rate budget deal with Plaid will continue their record-breaking NHS cuts, while we remain without crucial details on enterprise zones, solid decisions on business rates relief, and improvements to inward investment.
Welsh Conservatives are the only party with the action and ambition to achieve for Wales and help our country become stronger and more resilient than ever before.
Stephen Doughty admitted a turnout of 25.35% was 'disappointing', but he thought the increase in Labour's share of the vote since 2010 was 'remarkable'.
He told our Political Reporter Owain Phillips that his resounding victory 'shows that people are fed up of the policies of this coalition government and they want to see a different way ahead.'
The new MP for Cardiff South and Penarth, Stephen Doughty, says his victory was a 'resounding rejection' of the coalition government at Westminster. He pledged to serve 'humbly and faithfully'. His majority was 5,334, a small increase on the 4,709 that Labour predecessor Alun Michael won by in 2010.
- Stephen Doughty - Labour - 9,193
- Craig Williams - Conservative - 3,859
- Bablin Molik - Liberal Democrat - 2,103
- Luke Nicholas - Plaid Cymru - 1,854
- Simon Ziegler - UKIP - 1,179
- Anthony Slaughter - Green - 800
- Andrew Jordan - Socialist Labour - 235
- Robert Griffiths - Communist - 213
Labour have held on to the parliamentary seat of Cardiff South and Penarth in a by-election. Stephen Doughty, who has previously been the head of Oxfam Cymru, will be the new MP.
He replaces Alun Michael, MP since 1987, who stepped down to stand to become South Wales Police and Crime Commissioner. Labour has held the seat since 1945.
Narrowly more than one-quarter of the electorate voted in the Cardiff South and Penarth by-election. Ballots have now been verified, showing a turnout of 25.35%.
- 19,204 ballots were filled out
- 75,764 people in the constituency were eligible to vote
Labour's candidate - and the clear favourite to be the next MP for this constituency - Stephen Doughty was given a warm round of applause by a group of party members as he arrived at the count a few minutes ago.
The turnout for the Cardiff South and Penarth parliamentary by-election looks set to be just above 24%, the count manager has just announced. There are a handful of ballot boxes still to be verified.