More than 10,000 people have joined the Lib Dem party since it lost 48 of its 56 MPs on election day. The Labour Party has seen its membership boosted by nearly 30,000. So why do people join losing parties?

Lexi Rose has supported the Liberal Democrats since she was 18 years old.

But it wasn't until the party suffered a "catastrophic fall from grace" on 7 May that the 28-year-old freelance writer decided to join the party.

"It was a knee-jerk reaction. I woke up on Friday and was really angry and wanted to help," she says.

Image caption Lexi Rose joined the party because she wanted to help

Peter Sigrist, director of the International Community School in London, felt a similar urge.

"There was a personal, emotional response - Clegg's resignation speech struck a chord with me, and I felt the Lib Dems had been the victims of an electoral system which doesn't support smaller parties.

"But I also suddenly felt very strongly that the Lib Dems stood for the centre ground of politics, and they need to reclaim it," he says.

Image caption Peter Sigrist says he had an emotional and political reason for joining the Lib Dems

The 39-year-old hasn't always voted Lib Dem. He voted Conservative in the last election, and has voted for the Labour Party in the past.

He says the problem with the Lib Dem campaign was that people didn't know what the party stood for. But although he was initially despondent about the result, he now feels a sense of optimism.

"Hundreds of people have joined the party on social media. About 300 are coming to a gathering I've arranged at a pub on Monday night. I feel like politics might be changing, it might be becoming more relevant to people," he says.

In fact it's not just hundreds of people who have signed up. More than 10,000 people have joined the Lib Dem party since polling day, taking the membership to 55,649.

The Labour Party has also had a boost despite losing the election. About 29,100 people have become members, taking the party membership to 230,000.

Image copyright Alex Murray

Image copyright Alex Murray

A similar thing happened to the SNP after the Yes campaign lost the referendum.

Membership jumped from 25,642 at 17:00 on the day of the vote to 50,000 a week later. By the general election, the SNP had 105,000 members.

What does party membership entitle you to?

It varies from party to party, but generally; the chance to vote on selecting candidates, the right to attend party conferences and the right to stand as a candidate after about one year's membership.

In some parties, members play a more direct role in deciding party policy. They may have the right to vote on motions at the annual conference that decide the party's position on various issues, or debate policy issues at conference.

It's not unusual for political parties to receive a boost in membership after they lose an election, according to Dr Stephen Fisher, an expert in political sociology at Oxford University.

"With the Lib Dems and Labour, there is probably a feeling among those dismayed by the results that the party needs more support, and signing up will help them along," he says.

But he says it is hard to know how long people who join parties in such circumstances stay loyal.

Justin Fisher, professor of political science at Brunel University, agrees. "They can be like football fans and walk away when going gets tough," he says.

He says it's not just a political party's defeat that acts as a catalyst. Success or a sudden moment in the spotlight can also spur people on.

"There was a big spike when Blair became the leader of the Labour party and that carried on in the 1990s - it bucked a trend in Europe when party memberships were declining.

"And in 2001, when John Prescott punched a man in north Wales, Labour reported people joining because they approved of his actions," he says.

Image copyright Alex Murray

Who are the Lib Dem new members?

•Over half aged under 35

•82% have never been a member of the party before

•72% have never been involved in any sort of campaign before

•Oldest new member is 91

•Most new members in Sheffield, Bristol and Twickenham & Richmond

Party membership as a whole remains a minority pursuit. A recent House of Commons Library note shows that less than 1% of the UK electorate is now a member of the Conservative, Labour or Liberal Democrat Party, compared with 3.8% in 1983.

Smaller parties and nationalist parties have bucked this trend to some extent, according to author Richard Keen, since they have "risen markedly since the new millennium".

The SNP has gained another 7,300 members since polling day. Plaid Cymru has added 200 people, taking its total to 8,000, while the Green Party has added 3,721, totting up to 66,573. UKIP said it doesn't have any figures on new members.

The Conservative Party has also attracted new members, although it's not clear how many joined after polling day as the party said its membership was up by 30% this year, totalling 224,000.

Image caption Ash Chetri said he wanted to do something "meaningful"

So is the boost to losing parties a case of the British backing the underdog?

Ash Chetri, 23, from Ealing, says he felt an "urgency to do something meaningful" when Ed Miliband resigned.

"I don't think people fully appreciate something until it has gone.

"I felt the party would be looking for a new direction and became a member to ensure that my voice will contribute to the rebuilding process. I think young people like me want to make a difference at grassroots level. It's the first time I've joined the party, although I've always voted Labour," he says.

The student says he also feels an element of guilt that a "decent leader" did not go through, and lots of people made the mistake that the party "could tweet itself to victory".

"I believed Labour could get a minority government - this has been a huge wake-up call," he says.