Deputy Prime Minister Nick Clegg has congratulated Mike Thornton on his victory:
The leader of the UKIP party, Nigel Farage is already looking ahead to the future of his party.
Speaking to Daybreak he said this morning's result at Eastleigh was "really exciting", as the party gained so many votes from Tory, Labour and Lib Dem voters.
He said looking forward to to 2015, the party needs to focus on getting more members, and more presence in UKIP's "weaker parts of the country."
Speaking to Daybreak, Daily Mail journalist Andrew Pierce said that this morning's win at Eastleigh for the Liberal Democrats is a "complete disaster for the Conservative party."
The Lib Dems won by less than two thousand votes in the by-election, managing to hold off a UKIP surge.
The Daily Mirror's associate editor Kevin Maguire added that UKIP should be "deliriously happy" with their result, receiving more votes than the Conservative party.
He added: "It's a nightmare for David Cameron who played his Europe card, who thought that would stem the flood of Tory voters going to UKIP. It hasn't happened."
Conservative candidate Maria Hutchings, who came third, decided not to speak to reporters after the count at Eastleigh - and the result was an almighty scrum.
Interviews with the winning Lib Dem candidate, Mike Thornton; Nigel Farage, UKIP leader; George Hollingbery, Conservative MP for Meon Valley; and John Denham MP, Southampton Itchen.
This is how the share of the vote looked for the four main candidates:
- Mike Thornton (Liberal Democrat) - 32.1%
- Diane James (UKIP) - 27.8%
- Maria Hutchings (Conservative) - 25.4%
- John O'Farrell (Labour) - 9.8%
- Other - 4.9%
The Conservative candidate Maria Hutchings has refused all interviews and left the building by a side entrance amidst a media scrum.
The UKIP leader Nigel Farage has said he believes his party would have won given another week of campaigning, pointing out that UKIP did better in votes cast today as opposed to postal votes.
He told Sky News: "No-one can ever say that a vote for UKIP is a wasted vote. We're getting nearer and nearer."
The Liberal Democrat candidate won with a majority of 1,771 results, down from the 3,864 majority in 2010.