The scenes witnessed across London on Thursday transfixed the nation and scandalised many. But they also marked a raw coming-of-age – and, perhaps, a turning point in the fortunes of the three main parties

Sarah Lucas, a teacher from Hove in Sussex, watched the images flash onto her television screen: flames licking up in front of Big Ben; fireworks bursting in the air; eggs hurled by teenagers; masked youths charging at police officers.

It was Thursday night, and the news had seeped out into Parliament Square that the vote in the Commons, which would allow universities to almost treble tuition fees to £9,000 a year, had been won. It spread through the thousands of cold and tired protesters: students, lecturers, schoolchildren, parents, trade unionists and anarchists.

Lucas watched angrily. Before the election she had worked hard trying to persuade friends to back the Liberal Democrats. At 26, still paying off student debt, unable to get onto the housing ladder, she had thought the Lib Dems offered hope. "I saw them as the party for the young," she said. To her, the vote on fees was a broken promise.

Almost 60 miles to the north, the chants booming through Westminster grew louder as plumes of red-tinged smoke rose into the air and drifted towards the Houses of Parliament.

It was the perceived assault on university education that brought thousands of young people to the streets of the capital on Thursday. On previous days it had been economic policy. Tomorrow, it will be the decision to abolish the education maintenance allowance (EMA) for teenagers from poor backgrounds.

What has triggered this change? For years, the young have been dismissed as apathetic. What has happened to make tens of thousands of them pour on to the streets in the bitter cold – not once, but again and again; not just in London, but in Manchester, Birmingham and Leeds? What has sparked the re-emergence of student occupations in lecture theatres across the country? What is it about the coalition government and its policies that has ignited so much anger?

Shiv Malik, co-author of the book Jilted Generation: How Britain Has Bankrupted Its Youth, says the under-thirties feel betrayed – sold out in favour of their parents and grandparents. Fees, he argue, are just one part of the jigsaw. The 29-year-old took to the streets himself on Thursday, and was injured after being hit by a police baton. He argues that most of the protesters were not anarchists or socialists but young people whose instinct to revolt had been awakened for the first time.

"George Osborne kept his promises to the older generation – to keep their free eye tests, their winter fuel allowance, their free prescriptions, their free bus passes," says Malik. "Eighty per cent of winter fuel recipients are not winter-fuel poor. If you means-tested [them], you would make £2bn to spend on higher education."

He argues that what has particularly angered the young is David Cameron and Nick Clegg's insistence that the cuts are necessary to prevent heaping debt on to the next generation. "They have cut our futures and are lumbering us with debts anyway," he declares.

The shift in mood is perhaps most obvious inside the National Union of Students. Until recently, its president, Aaron Porter, had been attacked for being unwilling to fight, facing howls of protest from the left for giving up the battle for free higher education and instead accepting the principle of a "graduate contribution".

But he wanted a graduate tax – not annual fees of £9,000 a year. While the NUS marched against fees in 1998 and 2004, this year's revolt has been on a different scale. "There has been a build-up of issues – not just tuition fees but the EMA, youth unemployment, struggling to get onto the housing ladder and bleak prospects for the future – all coming together to spark a wave of protest," says Porter. "The NUS considers this level of youth activism to be unprecedented, perhaps since the 1960s."

Other organisations are involved too: UK Uncut, which has targeted high street chains in its campaign against tax avoidance; the Education Activist Network for lecturers and students; the National Campaign against Fees and Cuts, which grew from a meeting with 170 students.

The photographers who ran alongside the protesters on Thursday captured the defining moments of an extraordinary day: young people using metal poles to try to break into the Treasury; the Duchess of Cornwall open-mouthed as protesters attacked the car she and Prince Charles were travelling in; Charlie Gilmour, son of Pink Floyd guitarist David Gilmour, swinging by the union flag off the side of the Cenotaph.

It had started peacefully, but as evening slipped into night the scenes turned violent. The bright yellow jackets of the police disappeared, replaced by black riot gear, batons and shields.Some described it as reminiscent of the poll tax protests of 1990. Fifty people were injured, 33 were arrested, one police officer sustained a serious neck injury and one student, Alfie Meadows, suffered a stroke and required brain surgery after allegedly being struck by a police baton.

The protests opened a passionate debate about whether the violence had harmed the cause or helped by putting the story on the front page. Cameron reacted angrily to the "feral" behaviour, saying it was not just a "small minority". "There were quite a lot of people who were hell-bent on violence and destroying property," he said.

Questions also swirled about whether the police had gone too far. Protest leaders accused them of a heavy-handed and disproportionate response; students who had travelled to London with Meadows, for example, insisted he had been there to protest peacefully.

So, it seemed, had many others. "By the time the cuts are put into place, my uni will be hanging by a shoestring and the government want to charge people three times the amount," said Lucinda Hodge, 22, from Goldsmiths, University of London. "Politicians don't care about young people as we don't vote as much. We are just collateral damage."

Others had come from school and college. "There is a slim chance of going to university now," said Roze Brooks, 17. "Quite frankly I won't be able to pay," said Jack Jordan, 16.

There was even some sympathy in the right-wing press. While condemning the violence, the Daily Mail also commented: "We… worry that graduates will have to start paying this money back at about the time they are buying their first house and starting a family, crippling them financially just as they try to become fully fledged members of society."

Young people are discussing fears about their financial futures. "Debt for ever?" asked Holly Carlile, 22, from the University of Birmingham. "Will we ever be out of rented accommodation? How are we expected to put a single foot on the property ladder?" Jacob Burns, who studies at Goldsmiths, said he was increasingly pessimistic about ever being "debt free".Back in Hove, Lucas switched off the television. She felt the police and some protesters had gone too far and described the action as a "lost cause".

The demonstration may not have stopped the vote on fees, but it certainly has political implications, not least for the Liberal Democrats, who have seen their support among students collapse.

Other young people are angry too. Lucas said she would be unlikely to vote for them again, and she doubted that any of her friends would either. "They say it is a long time till the next election, but I don't think people will forget. They don't seem to have stood by anything I voted for apart from the pupil premium," Lucas said.

"I feel let down, like I was naive. It is a bit like a boyfriend has cheated on you. I will not be able to trust them again – and trust is an important thing when you are deciding who should run the country."

It is not just the Lib Dems that are suffering. Many students believe that all three parties failed to come clean about their ideas on higher education in their manifestos. On Thursday, one Tory MP was seen being harangued by three angry female students, decked out in coats and woolly hats for the protest.

"So what you are telling us is that we are not worth paying for," said one, raising her voice. Labour can challenge now, but many remember that it was Labour which set up the Browne review that led to the change in policy.

Nevertheless, the Lib Dems' problems are the most visible, not least because the party reached out to young people before the election. At the end of the debate on Thursday, the tension was clear as some of the party's MPs stayed rooted to their seats, abstaining, while others headed to different lobbies to vote for and against the policy.

Those closest to Clegg say they believe he will lose ground this week, but gain it, over time, for proving his resilience. They also point out that he argued against the party's fees position ahead of the election, believing it to be unrealistic, and that was why it did not become one of the four key promises on the front of the Lib Dem manifesto. The new tuition fee regime, they say, is fair and will support the poorest.

They also believe that lost student votes can be picked up elsewhere: private polling shows a boost of support among working-class women aged under 30.

But they also admit that the party and its leader have taken a heavy hit. "There was a tension in our brand that was revealed when we got into government," says one senior Lib Dem. "We are a party against broken promises. And we are also a party of plural politics, which means coalition and compromise, and that means we can't keep every promise we have made. The most real and visceral example of that so far is higher education – so it is much better to deal with it now rather than later."

He calls on voters to judge the fees policy on whether it opens the doors of universities wider to the poorest. "That is the test of fairness – and that is what you should hold us to account on."

Today, the party lays out the detailed plans for its pupil premium, which will mean £430 additional funding per year for each pupil on free school meals. That will rise to £625 by 2011-12. It will be followed by a week in which the focus will be on policies to support the poorest 16- to 19-year-olds. Deputy leader Simon Hughes, who abstained on Thursday, says: "I think everybody in the leadership of the Liberal Democrats knows that there is an urgent job to start addressing the concerns of 16- to 25-year-olds. I am clear this is a priority for me and I have made it clear to colleagues that this must be seen and heard to be an effective priority for the government."

It may be an uphill struggle. After all, the young don't need to take to the streets to protest – they have the internet too. Already the party is being parodied on social media sites, where a pre-election clip of Clegg calling for no more broken promises is doing the rounds. And today, a song on YouTube that has become an internet sensation is officially released as a single in a bid to make it to the number one spot for Christmas. The TUC have branded the song, "Liar Liar" by Captain Ska, the official tune of the anti-cuts movement.

The video features bleached images of Cameron, Osborne and Clegg. The Lib Dem leader is seen standing at a podium at the party's conference in Liverpool in September. "We are finally putting Liberal values at the heart of British government," he booms, before a woman's voice cuts across him. "He is a liar liar... You can't trust him, no, no, no, no." He has just over four years to prove them wrong.

• This article was amended on 15 December 2010 to correct a reference to the Duchess of York to the Duchess of Cornwall.