The former Conservative MP Louise Mensch, who quit her Corby seat to move to America, has commented on her party losing her seat in the by-election:
Very respectable result indeed for whole Tory team against local anger at my resignation for family. & 20 LibDem marginals on target list
Labour leader Ed Miliband said the Corby by-election showed that "Middle England is turning away from David Cameron and the Conservatives because it feels let down."
Labour leader Ed Miliband congratulated Andy Sawford on winning the Corby by-election. He said: "You have stood as a One Nation candidate for a One Nation Labour Party."
Thank you to the people of Corby and East Northamptonshire. I am very proud to be your MP and I won't let you down
Nigel Farage tells me UKIP's Corby and PCC results show that "politics in this country is changing".
Prime Minister David Cameron said of the Corby by-election: "It's a classic mid-term result and obviously made difficult by the fact that the Conservative MP left the seat in question."
It was the first time in 15 years that Labour has won a House of Commons seat from the Tories in a by-election, and victorious candidate Andy Sawford suggested it had set the party on track for a successful general election in 2015, declaring: "The road to Downing Street runs through Corby."
The Corby by-election saw 44.65% (35,665) of the electorate turnout to vote.