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 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.