Alex Beaton is a 22-year-old philosophy and economics undergraduate with a bushy beard, a blue stud in the lobe of his left ear and a gentle sense of the absurd. You might think of his politics as post-ideological – or, if you were being slightly less intellectual, absolutely all over the place. At the 2010 general election, he voted for the Liberal Democrats. He has very little time for either Labour or Ukip. And though he’d vote Green in an ideal world, he’s actually about to give his support to the Conservatives.

On a freezing cold Thursday afternoon, I meet Beaton in his home town of Warrington. We spend an hour chatting in a cafe, and I get a sharp sense of how politics works for someone for whom Margaret Thatcher is a figure from period dramas, and who remembers the Iraq war as something that happened just as he started secondary school.

Though he’s a student at Edinburgh University, Beaton is registered to vote in the knife-edge constituency of Warrington South. Between 1992 and 2010, it had a Labour MP, but five years ago, the Tories took it back. Now, it’s number 22 on the list of 27 seats Ed Miliband will need to win this May if Labour is to be the biggest party in the House of Commons, let alone get a parliamentary majority. By the same token, if the Conservatives lose it, David Cameron will surely be stuffed.

So Beaton has the privilege of a vote that will actually count, in a contest that seems to fit the 20th-century view of British general elections. Older readers will know the drill: the majority of people support the same party they always have, while in a small number of “swing” seats, a tiny number of votes pass between Labour and the Conservatives, and – thanks to our clunky electoral system – one of them comes out on top.

But this election promises to be very different. The fact that more and more people are changing the party they vote for sits behind some of the biggest recent political developments – not least the rise of Ukip, and the SNP’s seemingly unstoppable success in Scotland. Opinion polls suggest that the Conservative and Labour parties’ combined share of support is at an all-time low. Just to make things even more interesting, thanks to their role as the coalition’s flak-catchers, the Lib Dems, traditionally the favoured option for people who have had enough of the old duopoly, seem in danger of borderline extinction, and the Greens claim to be in the midst of a surge.

Beaton is a prime example of a generation that is driving a lot of these changes. His background is not steeped in one party. His mum, a wheelchair user, “isn’t that into politics: she’s more on the outside, getting pissed off with it all”; his dad, an accountant, has recently been “in and out of work” and has “completely changed – he used to buy the Telegraph, but now he’s to the left of Tony Benn”. Beaton is keenly interested in politics, but apparently free of political loyalty. “It’s just about budgets now, isn’t it?” he says at one point.

He voted Lib Dem five years ago because they “seemed a good alternative: something new; something a bit different. Vince Cable was a big part of it. I liked him a lot. He was the only one who managed to call the crash, wasn’t he? And I was a bit bored with the main two parties.”

But on 7 May this year, Beaton will switch to the Conservatives. He says there’s more of a sense of urgency this time: the seat where he’ll vote will be won by the Tories or Labour, and he’d rather have the former in government. “The economy’s the only thing that matters, really. Everything feeds off that. And, as far as that’s concerned, the Conservatives are a safer bet. There’s a lot they’ve done that I don’t like. But that’s the main, solid reason.”

He looks surprised at himself, perhaps because he fancies following university with a job in the public sector to which George Osborne is set to take an even bigger axe – the NHS, or the civil service. But as his tangled-up calculations prove, when politics is cut loose from its old moorings and people change party as often as they change their phone, all kinds of strange things can happen.

Before Christmas, the Guardian posted an online survey asking people if they planned to switch party at the coming election. We got more than 1,000 replies, from people across England, Wales and Scotland. Some of those I meet, like Beaton, carry almost no political baggage. But for others, the past is as important as the present: Thatcher and Blair are mentioned more than Cameron, Miliband and Clegg. People talk about family history, deep questions of identity – and, often, a profound sense of right and wrong. Judging by what they have to say, Britain is not quite the switched-off, eternally cynical place we are told about; nor is it a three-party country any longer.

Steve Gulati: ‘It felt dirty, a terrible thing to do: voting Liberal to keep the Tories out.’ Photograph: Suki Dhanda/Guardian

The week before my trip to Warrington, I arrive in Solihull: the 10th most marginal seat in the UK, held by the Lib Dems last time by the squeakiest of margins. I’ve come to meet 42-year-old Steve Gulati, who last time voted for Clegg’s party to keep the Tories out and watched, horrified, as the Lib Dems achieved the absolute reverse.

We meet in a cafe inside the town’s art centre. Gulati was a full-time manager in the NHS before he was made redundant. He now lectures at Birmingham University, and does freelance human resources work for the health service. In 2013, he was involved in implementing the more grisly end of the government’s controversial health service reforms. “Two years ago, on Christmas Eve, I was giving people their notice,” he tells me with a grimace. “I reckon we made 130-odd people redundant.”

His politics run deep. In the 1960s, his parents emigrated to Britain from the Punjab: somewhere with “quite a socialist, leftwing culture”. They were teachers, encouraged to come to work in British schools, but when they arrived, they discovered their qualifications were not recognised. His dad spent years working in an electronics factory before he got a UK teaching qualification; his mum never made it to the classroom, instead working for paltry wages for a food processing company.

“But the thing that made them political,” Gulati says, “was Enoch Powell.” The infamous Tory politician made his anti-immigration “rivers of blood” speech in April 1968, and instantly became a hero for people bitterly opposed to immigration. Gulati’s parents suddenly felt scared.

His dad died last year. “I was going through his papers for weeks afterwards, and I found all these newspaper clippings about Powell and his speech, and racial attacks. It really electrified them. It was all part of ‘Labour is good for us – the Tories are bad for us; the Tories are racists.’”

This view of the two big parties defined the way Gulati voted until 2010. “Labour was obviously going to lose. I was still Labour in my heart. But the thing I’m most fearful of is a Tory government, and Solihull is a Tory/Lib Dem marginal: a very, very close-run seat. So I had long discussions with my wife before the election in 2010. I was considering voting tactically: voting Liberal to keep the Tories out.” What did his dad think? “I don’t think I even told him. It felt dirty, a terrible thing to do. I had a physical feeling the first time I considered it: a kind of tingling down my back.” Still, on election day, he did the deed.

In the strange, surreal days of early May 2010, the coalition began to be stitched together. “I can’t describe the passion, the negative passion, I felt then,” he says. “I felt so betrayed. To think of our local MP going into the division lobbies with Osborne and Cameron and these rightwing bastards – it was disgraceful. Immoral.”

Now, whatever the consequences, Gulati is going to vote Labour again. “What would change it for me is if the Lib Dems did what the SNP have done in Scotland, and said, ‘Under no circumstances would we have a coalition with the Tories.’ Then I would vote tactically to keep the bastards out. But I did that last time, didn’t I?”

Sarah Roberts: she was a Lib Dem. This year, she’s going Green. Photograph: Suki Dhanda/Guardian

The next day, I arrive in another knife-edge seat – Manchester Withington, a Labour/Lib Dem marginal, held by Clegg’s lot by a mere 1,894 votes – to talk to someone else who is going to turn her back on tactical voting and go with her heart. Sarah Roberts, 28, is a primary schoolteacher in nearby Levenshulme. She grew up in the constituency of Sheffield Hallam – and the first vote she cast was for Nick Clegg, who became her MP in 2005. “I feel like I grew up with him,” she says. “His office is at the bottom of my mum and dad’s street. We used to drive past his house.” He visited her school and enthused about the importance of education, and university in particular. “He seemed trustworthy. I was on my way to university, and there was so much talk about tuition fees. He had a policy of making sure more people could go to university, and they weren’t going to be saddled with debt.”

So she voted Lib Dem again in 2010, but the arrival of the coalition left her feeling “gutted – I just thought, ‘My vote’s caused this.’” When the party surrendered to the Tory policy on tuition fees, she concluded that Clegg was going to be a “wet lettuce”. Now she regularly finds herself getting angry about the state of society, something she witnesses from the sharp end. A majority of the kids in her year three class have English as an additional language, and she has direct experience of kids coming to school hungry, or wearing “shoes that don’t fit, with holes in”. It makes her furious “that the children in my class won’t grow up with as much equality in their lives as I’ve had: they won’t get as good life chances. The odds are stacked against them, and that’s getting worse.”

Rather than vote Labour (“I just see them as all talk, no action”), she is set on voting Green. A bit of this, she says, goes back to her mum and dad, who have always supported the Greens and brought her up “with a socialist viewpoint”. But mainly she has made the decision on the basis of careful thought. “I’ve got to the age where I’m a lot more politically aware. And I don’t think I could live with myself, voting for something I don’t believe in. I’ve read a lot of the Greens’ policies, and they’re exactly the kind of things I’d like to happen to the country.”

What, I wonder, does she make of the fate of Clegg? “He seems a bit like a broken man. But he’s got enough money. I feel more sorry for people getting evicted because of the bedroom tax.”

Roberts is one of the rising number of voters who are opting out of traditional three-party politics. Such behaviour is a relatively new phenomenon in England, but in Scotland the Tories have long been a negligible force, the Lib Dems look doomed, and even the Labour party seems to be a declining force. The Scottish National party has emerged from its supposed loss in last year’s independence referendum to dominate Scottish politics: recent opinion polling for the general election puts the SNP at 43% in Scotland, suggesting that in May it could well subject Labour to a real blood bath.

Hannah Roberts, 23, is from Preston, Lancashire. She came to Scotland to do a degree at Glasgow School of Art. Having graduated, and worked as a fishmonger, she now wants to do a PhD, though she’s about to start a new job as a waitress. Her background, she says, “sounds working class”: her dad was a joiner and her mum worked for Matalan. “I suppose I felt… maybe lower middle class, or aspirational working class,” she says, looking slightly pained. “Something like that, anyway.”

We meet in the Glad Cafe on the south side of Glasgow, a hang-out that gives off the scent of the creative Scots bohemia that defined a corner of the recent referendum campaign. In 2010, Roberts voted Labour. “It was to avoid the Tories getting in,” she says. “Anything else just seemed too risky.” By that point, she thought of herself as firmly on the left, which she traces to “not having much money” and her bond with her eldest brother, who has incapacitating OCD. “I’ve had experience of people who are… vulnerable, I guess. Knowing one of those people very closely, loving one of those people, and wanting them to do as well as everybody else.”

When she first came to Scotland, she found the idea of independence problematic. “It’s a difficult thing to think about if you’re English, particularly if you’re from the north.” But when the referendum campaign flared to life last year, she started thinking unexpected thoughts. “An opportunity actually existed to change things. That was a totally new feeling to me. Before, I would just vote Labour to stop the Tories; I didn’t think any of the things I believed in were feasible. But now they were.”

She voted yes. So how did she feel when the no side won? “Pretty devastated. I cried at work. I felt a huge chance had been missed. I thought about the future, and all of my opportunities – and, if I have kids, their opportunities. And I just felt really depressed that nothing was likely to change.”

There is a crack in her voice even now. “I’m very good at crying,” she says. “I cry quite a lot.”

In May, she’ll vote for the SNP in Glasgow South, a seemingly safe Labour constituency – though with some predictions suggesting that Scotland’s ruling party could take all but 10 Labour Westminster seats in Scotland, you never know. “It’s hard to sound like you’re not romanticising it, but I get the impression that the SNP really do care about the people of Scotland. They want to make Scotland a country where there’s more social equality; where there isn’t as much suffering. The most important thing is, I’ve got to the stage where I don’t want to vote for the lesser of two evils any more.”

The next day, a 10-minute train ride takes me to Paisley, on the western edge of Glasgow. I’ve come to meet 56-year-old Dorothy McManus, a staff nurse in the mental health wards of a local hospital. She’s another Labour to SNP switcher, who responded to our survey with the pithiest of explanations: “Labour no longer hold the values they once had and are just red Tories.”

We drink terrifyingly strong tea in a cafe in the town’s shopping centre, and McManus tells me about her three grown-up children; in August she’ll become a great-grandmother.

Until now, she has always supported Labour, with one exception: 1979, when she voted for Thatcher. “I thought, naively, a woman might make a difference.” She quickly changed her mind. Labour “seemed to fight for the working man. But Tony Blair changed it. He moved to the right; he was looking to appease middle-class people. And, by then, this place was dead.”

Paisley has always been a Labour town, but the people in charge of the council, she says, reached a peak of complacency and arrogance when they put up “stupid sculptures” and refurbished their own offices. Over time, her instinctive loyalty to Labour started to weaken: the Iraq war and 2009’s expenses crisis were part of it. “A couple of times at the last few elections, I’ve kind of swithered,” she says, miming the flitting of her pencil from one box to another. “But then it’s been, ‘Stick with what you know.’”

Her favourite politician is Alex Salmond. Though she has friends and colleagues who think he’s something of a rogue, “I trust him to do what’s best for Scotland.” And his party? “They’re better than the rest. They’ve done reasonably well for Scotland with the limited budget they’ve had. Some of the childcare things, free prescriptions definitely. Free bus travel, which my husband got for the first time in October. He’s loving it.”

So McManus, too, is moving from Labour to the SNP. In just about everything, she says, one plain fact burns through: that Scotland now has its own politics, and her decision to leave Labour behind is one small sign of a much bigger shift, which she thinks is rooted in deep matters of national identity. “Scottish people, on the whole, are more altruistic. They look after each other more; they think about people other than themselves. I don’t think we’re selfish, generally. We’re different.”

From whom? “People in England, if I’m honest.”

Tom Taylor-Duxbury: ‘Ukip would get us out of Europe. They’re incompetent on other things.’ Photograph: Suki Dhanda/Guardian

And so to the UK Independence party. Getting to talk to Ukip converts does not prove easy: most of the relevant respondents to our survey want to remain anonymous. Only two agree to talk.

One is 66-year-old Tom Taylor-Duxbury, a lifelong Conservative voter who lives in Ludlow, Shropshire. An engineer turned entrepreneur who grew up in Bolton, Lancashire, he says his politics go back to a phrase his father used: “I’ll never be rich enough to be a socialist.” Too many on the left “have never had dirty fingernails. They’ve not realised how difficult it is to earn a quid. I don’t expect anything from anybody. I’ve always been right of centre.”

He is switching party for one reason only: the EU, and his deep belief that Britain should get out as quickly as possible. “The world is a huge marketplace, and that’s what we should be going for, rather than being drawn into the black hole of Europe.” The EU is a “political nightmare. It’s diluted our democracy to the extent that it’s a shamocracy. Politics is way too remote from me.”

He doesn’t trust Cameron: he promised a referendum on the EU’s Lisbon treaty and then decided against it, so “empirically, the guy’s a liar”. In some alternative universe, Taylor-Duxbury would think about voting Labour: “If Ed Miliband came out tomorrow and said, ‘We will give you a referendum the day after we get into power’, he’d get my vote.” He is, he agrees, a single-issue voter, and only Ukip has the answer he wants. “I’m not bothered with the other politics of it,” he says, and just to prove it says some non-Ukip-ish things about immigration (“The thing you’ve got to ask is, why have our locals got such a crap work ethic?”). “Ukip would get us out of Europe,” he concludes. “Then they might fall at the first hurdle. They probably would: they’re incompetent on a lot of other things.”

Helen Gradwell, 38, is also from Bolton, but she has stayed put. After a degree in psychology and sociology, she became a secondary schoolteacher. She has since developed hemiplegic migraine – “Basically, really bad pain down one side of my body” – and now works as a private tutor, “earning a lot less”. The morning I visit her terraced house, she is watching Dallas, but says she watches all the political coverage: “I’m really sad,” she says. “I even watch the Daily Politics.”

She explains her 20-year political journey. “I’ve always been more leftwing, so I started off Labour. But with Blair, I just thought, ‘I’m not voting for him again.’ I thought he was a charlatan almost immediately. Completely fake; just Thatcher-lite.”

Helen Gradwell: ‘I started off Labour. I suppose I’ve always wanted the protest vote.’ Photograph: Suki Dhanda/Guardian

She moved to the Lib Dems. “I’ve always been interested in social justice, and they were the only ones offering anything remotely like that. Growing up in Bolton, I’ve seen a lot of people who didn’t have the best start in life, and I’ve always wanted to make that better.” In retrospect, moving beyond Labour and the Tories always had an appeal: “I suppose I’ve always wanted to be a protest voter.”

Now she is going to vote Ukip, and protest about one issue above all others: immigration. “I’m very concerned about the kids I teach and their futures. When I talk about British kids, the colour of their skin’s got nothing to do with it. I’ve taught in inner-city Manchester, and Oldham, where there’s a large proportion of black and Asian kids – and with second-generation immigrants, they’re often the worst affected by immigration, in terms of job opportunities. They really struggle.” She barely pauses for breath. “I’ve always been about a fair society, and what really annoys me is metropolitan, elite, north London politicians who haven’t got a clue. They think a fair society is about being nice to ethnic minorities. And yeah, that’s lovely. But what about the working class? Labour just don’t care about the working class any more; they’ve just abandoned them. All they care about is issues: racism, feminism, gay marriage. They should get back to what the party was set up for, which is representing working people.

“Mass immigration is a capitalist tool,” she concludes. “It’s exploitation. It benefits nobody but multinational companies. Why can’t Labour see that?”

The argument is well-worn, and I give her the well-worn response: that people from overseas are doing jobs that British people simply don’t want. “That’s the fault of our education system. There are people who aren’t equipped to work; who can’t work, because the education system’s so rubbish.”

I ask how she feels about the seemingly endless reports of Ukip candidates and councillors voicing ugly opinions. People from the other parties do the same, she says: “But if it’s not Ukip, the national media don’t want to know.”

She talks about having leftwing values, but she’s about to vote for a party led by that unabashed Thatcherite Nigel Farage. How does that work?

“It doesn’t matter. It’s whether or not he takes on board what ordinary people are saying and does something about it. I’ve heard all this stuff about, ‘You can’t support him if you’re leftwing, because he went to a private school.’ It doesn’t make any difference. He can communicate with normal people. All the others can’t.”

The most popular directions of travel for Britain’s political switchers are pretty clear: from the Lib Dems to Labour, the Tories and Labour to Ukip, Labour to the SNP. But one or two contrarians will jump in altogether more unexpected directions, as I discover when I head up the M62 to Yorkshire.

In the cosy village of Burley in Wharfedale, I meet Nick Errington, 40, an insurance claims manager who works in Leeds (Britain’s second-biggest financial centre). With his wife and two children, he lives in an upmarket development built on the site of an old mental hospital, in a pristine, three-storey house.

Errington is from a Labour family; his grandmother was a card-carrying communist. He grew up in Barnsley, and has vivid memories of the miners’ strike. But his history reflects what happened to Labour from the mid-1990s onwards: its embrace of the free market, and Blair’s quest to pull it away from its political past. “My dad was a socialist,” he says. “I’m more centre. I want to be successful. I’m more money-focused than he was.”

Having voted Labour with reservations in 2010, he reacted to the arrival of Ed Miliband with an anxiety that hasn’t gone away. Among other worries was the fact that the new leader had edged past his brother thanks to votes from trade union members: “I thought, I don’t want the unions dictating to Labour what their policies should be. And there was a lurch to the left. I don’t think Britain is a leftwing kind of country, and I don’t think it’s ever going to be. And if you push that view too much, you just end up with rightwing governments.”

Errington also has more direct criticisms. He imagines future international summits, and fears the worst. “My problem with Ed Miliband is, he’s going to be stood next to Luxembourg.” All told, he misses Blair. “He could come back, as far as I’m concerned. I’d vote for him. I’m probably in a minority.” He laughs.

His antipathy to the Labour leader is so deep, he’s decided to vote Lib Dem. “I couldn’t vote for the Conservatives or Ukip. And it’s like a note to Ed Miliband. If other people do the same thing, he might say, ‘Hold on a minute – we’re not on the right track.’ Or he might move on. They might even get his brother back.”

Howard Shaw: ‘As a Christian, it’s difficult to support the party that brought in the bedroom tax.’ Photograph: Suki Dhanda/Guardian

My journey ends in Reading with slightly better news for the Labour party. In a crowded cafe, I meet 38-year-old Howard Shaw. He teaches politics and history at a local independent school; he is also a committed Christian. Until 2005, he was a member of the Conservative party.

Shaw grew up in Burnley. His dad, who had a small textiles business, “was very passionate about Margaret Thatcher”, and Shaw became an active Tory. By the time he entered his 30s, though, he was troubled by the narrow-mindedness of a lot of his Tory comrades. Still, the arrival of David Cameron momentarily raised his spirits, and he once again voted Conservative in 2010. “I liked the idea of the Big Society, and I felt the country did need a change. At the beginning, Cameron did appear to be quite reasonable.”

Since then, things have gone sour. “It stuck in my mind when George Osborne talked about people going to work and seeing other people’s curtains drawn because they live on benefits. That’s ridiculous, and it’s inviting people to judge. Government should be something respectable, for all the people – not just some who are seen as, ‘They’re hardworking, so they’re all right.’ Some people can’t be hardworking, for whatever reason.

“I don’t want to use Christian-ese with you,” he adds, “but getting to know Jesus, as the person in the Bible with a commitment to social justice and equality and things like that, it’s hard to support the party that brought in the bedroom tax.”

Shaw lives in the constituency of Wokingham, a safe Tory seat held by rightwinger John Redwood. In May, he says, he will probably vote Labour. “I’d like a government that is more socially just; more unifying. We’re a very fragmented, fractured country. The Conservatives have contributed to that. And from what I’m hearing from them now, I think it’d only get worse. It’s not a future I want.”

For a moment, I imagine I can hear loud rejoicing, drifting up the Thames from Labour HQ. Then I go back to the railway station, buy the papers and receive my daily reminder of the uncertain place in which our politicians find themselves.

The election is now barely three months away. The final result is still anyone’s guess: across the country, everything will hang on those who change parties, and which ones they choose. When voters switch, perhaps, raw democracy rears its head; this time, if only for a day, power may actually lie with the people.