When Gerwald Claus-Brunner walked into the debating chamber of Berlin's state parliament on Thursday morning, you could be forgiven for thinking he had got lost on the way to the boiler room. Dressed in bright orange dungarees, a bandana and clodhopping bovver boots, he very much looked as if he had arrived to fix the heating. Instead, the towering 39-year-old fished a folder out of the front pocket of his dungarees and sat down among the parliament's 149 deputies.

Perhaps the Long John Silver headscarf should have given him away: Claus-Brunner, an electrician by trade, is one of 15 members of the Pirate party who confounded expectations at Berlin's elections in September by winning a seat at the expense of the Free Democrats, Angela Merkel's federal coalition partners. His parliamentary comrades include a 19-year-old student (the only female Pirate parliamentarian) and an unemployed physicist. The average age of the faction is just 29.

The party, a spin-off from the Swedish Pirate Bay hacker movement, was formed in 2006. For most of those five years they were largely ignored. Few took them seriously, right up to polling day. They certainly didn't seem to themselves, campaigning with lackadaisical slogans such as "Do whatever you like" and "Finally: some normal people", rather than troubling the electorate with proper policies on knotty issues such as healthcare or education.

The Pirates were elected on a manifesto of largely fantastical ideas. They promoted free public transport for all in perennially broke Berlin, civil partnerships for three or more people and a universal state income for those in and out of work, for example – as well as a firm and demonstrable commitment to transparency. Those who voted for them are unlikely to have ever believed their utopian dreams would ever become reality. Nonetheless, the Pirates won 8.9% of the vote in the German capital, and a poll on Friday suggested that were there a general election on Sunday, they would gain around 7% of the vote nationally: enough to send a few MPs to shake some feathers in the Bundestag. Though none of the established German parties are likely to want the unpredictable Pirates in a coalition, in a federal parliament where the government had only the slimmest majority, votes from some wayward Pirates could be decisive.

What should worry the political establishment is that the Pirates aren't a Berlin anomaly. They cannot be written off as the sort of thing that could only happen in the über permissive, stubbornly alternative German capital. All over Europe, new, leftfield (and sometimes rightwing) political parties are being taken seriously at the ballot box. Each has wildly different obsessions. The one thing they all share is the idea – being played out very visually in the occupations in Wall Street, London and Frankfurt – that the established way of doing politics is not working.

A Hungarian party represents this notion most graphically: Lehet Más a Politika (LMP), or Politics Can Be Different, won 16 seats in the national assembly last year. It has its roots in civil society and the green and anti-globalisation movements. The LMP deputy Virag Kaufer, 36, is in many ways typical of the new breed of European politician. A former campaigner for Oxfam and other NGOs, she says her party was able to get into parliament within two years of formation because it offered an alternative. "Hungarians are tired of the arrogance and ignorance of the political elites and their inability to change the current situation," she said.

Most ordinary Hungarians believe their lives have got worse 22 years after the fall of the Iron Curtain, said Kaufer. "The class divide has definitely increased since the end of communism, and people are fed up of seeing the political elite with their privileges refusing to listen to the common people." Denied regular access to the mainstream media, which Kaufer claims is being increasingly constrained by the ruling Fidesz party, LMP has had to be more creative to get its message across. She and her colleagues have started wearing slogan T-shirts in parliament, printed with old quotes from the ruling elite to show the chasm between what they say and what they do. "Social media is also very important for us – all of our MPs have Facebook sites, some blog, we're using Twitter more and more," she added.

Like Berlin's Pirate party, which has developed a software system called LiquidFeedback, allowing ordinary Germans the opportunity to propose policies, LMP is introducing an interactive function on its website inviting Hungarians to log government cuts. The party also asks voters to submit parliamentary questions and then invites them to the national assembly in Budapest on the day their question is put to the prime minister, Viktor Orbán, or his ministers.

Kaufer believes her party's success is part of a global trend. "All over Europe there is the same disillusionment with the political elite. You can see this with the Occupy Movement in Wall Street and elsewhere. People are demanding to be listened to, especially young people. They have nothing to lose – unemployment hasn't been this bad for a long time. I think this is really the last chance we have to change attitudes and listen to the 99%. I am pleased that people are mobilising themselves. It shows they still believe in democracy. They could show their disillusionment in much more radical ways."

On the ground at the Frankfurt occupation in front of the European Central Bank, protesters say they have lost faith in mainstream politics. "I don't think the established parties speak for me," said 24-year-old Martin from Berlin, who voted for the Animal Rights party in the last federal election in 2009. In the recent Berlin elections, however, he plumped for the Pirates. "I think they are a step towards change," he said, "but I don't honestly think they will be able to achieve much within the current party political system in Germany."

Yet to understand the influence even a small party can have, look back just a fortnight ago to what happened in the Slovakian parliament in Bratislava. There, with the eyes of the world watching, one small party managed to sabotage the first vote on the bailout fund, throwing a temporary spanner in the works to save Greece and other countries from collapse.

The doggedly free marketeering Freedom and Solidarity (SaS) party was set up only in 2009 after a small group of businessmen and economists decided to "stop grumbling about the conditions in Slovakia" and get organised, as the chairman, Richard Sulik, puts it. But after winning 12% in last year's general election, its 22 MPs were invited to make up the numbers in a precarious four-party ruling coalition and found itself with influence way out of proportion with its size. Sulik, one of the architects of Slovakia's 20% flat tax, was fiercely opposed to the European Financial Stability Facility (EFSF) bailout fund. "Just like it is impossible to extinguish fire with a fan, it is equally impossible to solve the debt crisis with new debts," said Sulik in party pamphlet which called the EFSF "a road to socialism" (a potent threat in a post-communist country). When all 22 of its MPs voted against the bill, the motion failed and the government collapsed.

In Poland earlier this month, another brand new party shocked the political establishment with its electoral success. Palikot's Movement (RP), named after its charismatic founder, Janusz Palikot, was underestimated by most politicos. Before election day on 9 October, one analyst, Bartok Nowak from the Centre for International Relations in Warsaw, told the Guardian that he would be "very surprised" if RP got over the 5% threshold needed to enter parliament.

Palikot, a former MP from the ruling Civic Platform party with a peerless talent for publicity, would certainly win a lot of votes in his Warsaw constituency, said Nowak. "But there's only one Janusz Palikot. All of the rest of the RP candidates standing elsewhere are unknown." On Friday, Nowak admitted he had underestimated Palikot. "I was surprised, but clearly Palikot tapped into something, especially among young people. They want more personal freedoms, they want the church to have less influence in public life, and they want Poland to be modernised." While the Polish prime minister keeps a low media profile as he constructs his cabinet, Palikot has filled the news vacuum by proposing two new laws which parliament will have to debate. All week the Polish media has been obsessing over each - one will see the cross taken down from the debating chamber in the Sejm, the Polish parliament, and the other proposes civil partnerships for gay people.

Nowak believes that Palikot will be able to shape both public debate and government policy in its forthcoming term. Whether the Pirates will be able to turn their talent for garnering publicity into adoptable policies is unclear. In other words: "Will they mess it up?" asked Sebastian Dullien, senior policy advisor at the European Council on Foreign Relations in Berlin. "They are getting paid salaries now – there is money to waste. There are standards they could fail to live up to. They have to prove that they are not just a joke."

A field trip taken by three of the Berlin Pirates last week suggests they may not be taking the politics of business all that seriously. At their own cost, they flew to Iceland to visit Besti flokkurinn – the Best party – which won civic elections in Reykjavik last year. It is run by Jo[acute]n Gonnir, a comedian and singer in a punk band, who won after promising his party would break all of its manifesto pledges, which included getting a polar bear for Reykjavik Zoo and free admission to all municipal swimming pools (plus free towels for all).

On their return, Christopher Lauer, one of the travelling Pirates, announced at their weekly faction meeting that the trip had gone "really well". The Best party was interested in adopting LiquidFeedback, said Lauer, and the two parties signed a memorandum of agreement. A concrete achievement? Perhaps not. It was a "declaration on nothing"

Born in Sweden

Sweden is the birthplace of the Pirate political movement, which scored a big electoral success in Berlin last month. The Swedish Pirate party, Piratpartiet, was formed in 2006 and has two MEPs. It has inspired spin-offs in 26 other countries, all campaigning to reform copyright and patent laws and protect an individual's right to privacy. The Pirates dream of making the internet "the greatest library ever created" by limiting copyright on all "aesthetic works" to five years, and believe scrapping medical patents would save millions of lives.