The Scottish National party (SNP) has pulled off a remarkable by-election victory in Glasgow East, winning a 22.5 per cent swing against Labour. Here's instant reaction from all the main parties.
SNP - Calum Cashley
"There's several wry smiles around the place. We're delighted - we always thought we could win it, but actually being proven that we can is great. This is the third safest seat in Scotland. We've taken it now so it's now there's not a safe seat in Scotland. We think we can move Scotland forward.
"The Labour party was in trouble before now. I think now they have to go away and think about what they're for - they have to be re-examine where they are. They've taken the people of Scotland for granted for too long.
"If it was just a standard by-election then you wouldn't expect this kind of reaction. We were obviously delighted but it's not just a swing in a seat - it's a general movement throughout Scotland."
Scottish Conservatives - Ramsay Jones
"We came into this election telling ourselves our primary goal was getting into third place - we've come out of it with nearly twice the Lib Dem vote. We've shown despite the enormous squeeze that we can fight an election in the [Conservatives'] 401st most winnable seat.
"It was a big squeeze but our vote has held up. We've shown tonight Scottish politics is a three-horse race. I think, in a general election, there are really only two parties that can form a UK government. Then there's the choice between an ailing Labour party and the rejuvenated Conservatives. We can come away with our head held high."
Scottish Liberal Democrats - spokesperson
"There's no doubt we got squeezed in this election. Soft Labour votes transferred directly to the SNP and not the other parties.
"I don't think it's a problem generally in Scotland. If you travel a few miles north to the Glasgow North constituency we're in with a great shot at the next election.
"I think we've seen in this election it's a battle between two governments and we've suffered because of that."
Scottish Labour - spokesperson
"This is a very disappointing result for us.
"Margaret was an outstanding candidate.
"We will of course work hard to win back the trust of the people of Glasgow
East at the next general election because we will always stand up for the