Nearly half of Britons say they are angry with politics and politicians, according to a Guardian/ICM poll analysing the disconnect between British people and their democracy.

The research, which explores the reasons behind the precipitous drop in voter turnout – particularly among under-30s – finds that it is anger with the political class and broken promises made by high-profile figures that most rile voters, rather than boredom with Westminster.

Asked for the single word best describing "how or what you instinctively feel" about politics and politicians in general, 47% of respondents answered "angry", against 25% who said they were chiefly "bored".

Negative sentiments vastly outnumber positive, with only 16% reporting feeling "respectful" towards people doing a difficult job, while a vanishingly small proportion of 2% claim to feel "inspired".

Responding to fears about disengagement by young people from politics, the Tory MP Chloe Smith, a former minister at 31, told the Guardian there was a danger of a political disconnect between young and old, with "generations far apart and not talking to each other". One of her ministerial briefs included improving voter engagement.

"I think there is an existential problem coming for traditional forms of British democracy, which it is in everyone's interests, all of us as democrats, to respond to," she said. "We have to demonstrate what politics is for, why a young person's individual action in voting matters."

When Harold Wilson won the 1964 election, more than three quarters of people cast their vote and turnout was roughly equal across the generations. But according to data from Ipsos Mori, at the last election 76% of over-65s were still voting, while only 44% aged 18-24 were going to the ballot box.

Rage is the dominant sentiment across just about every sub-stratum of the electorate, but is especially marked among men, northerners, voters over 45 and the lower DE occupational grade.

Labour voters, too, are disproportionately cross. But supporters of Ukip, the party that put itself on the map in 2013 with big gains in local elections, reflect the mood of the times most intensely: more than two-thirds, 68%, say the thought of politics and politicians makes them more angry than anything else.

Deborah Mattinson, a former pollster to Gordon Brown and now an expert at BritainThinks, believes politicians have not begun to grasp the scale of the problem. "Voter disengagement is getting worse and worse," she says. "Nobody is really taking it seriously enough."

Recent high-profile celebrity interventions on the subject have served to underline the growing disconnection. The former England footballer Michael Owen told the Guardian for the paper's series on voter apathy that he had never voted.

Russell Brand expressed the disaffection of many in October when he told Jeremy Paxman on Newsnight that he had never voted because he "can't be arsed", adding later: "The only reason to vote is if the vote represents power or change. I don't think it does."

After the interview, which received more than 10m hits on YouTube, Paxman said he understood Brand's decision, dubbing Westminster politics a "green-bench pantomime … a remote and self-important echo-chamber".

Reflecting such sentiments, the polling shows that ennui is more marked among the young, rivalling fury as the dominant feeling about politics among voters aged 18-24, who are evenly split 34%-34% between boredom and anger.

Boredom is marked in one other group, too – those voters of all ages who admit to being unlikely to vote. But even among those who rate their chance of turning out as four or lower on a 10-point scale, the angry marginally outnumber the bored, by 41% to 40%. When asked what puts people off voting, the cause of that anger is the perception that politicians do not keep their promises. Nearly two voters in every three, 64%, nominated the failure of governments to honour their pledges as something that would put them off casting a ballot – higher than any other factor.

In the week that the former Labour minister Denis MacShane was jailed for fraud, the continuing damage done to parliament's reputation by the expenses scandal of 2009 is also plain – 46% of respondents identify the sense that "MPs are just on the take" as a thought that would discourage them from turning up at the polling station.

Only around a third of potential voters, 34% of the total, say they are put off by careerist candidates who "don't say what they believe". Just 26% regard the parties as "so similar that [voting] makes little difference", and only 25% see the failure of the parties to "represent my mix of views" as a particular problem.

Meanwhile, the mechanics of democracy – the focus of thinktank proposals for automatic postal ballots or weekend voting – emerge as a virtual irrelevance.

Only 2% of the electorate regard the inconvenience of registering and then casting a vote as a reason not to do so, suggesting that proposed measures such as weekend or electronic voting are unlikely to make a big difference to election turnout.

Other findings though suggest that Britons remain convinced that politics matters. An overwhelming 86% told ICM that the "decisions politicians make" are either "very important" or "fairly important" to their own lives, as against just one in ten who said that such choices were "not that" or "not at all" important in day-to-day life. And there is remarkably little difference between voters and non-voters here: even among those unlikely to turn-out some 80% do believe that political choices will affect them.

Furthermore, Britons continue to talk politics regularly. A clear majority of the electorate as a whole, 62% of respondents, claim to discuss "politics or the sort of issues affected by politics" with friends and family at least once every fortnight, and a substantial minority of 29% claims to do so at least "every few days". Across the population, the pollster estimates an average of 72 political discussions a year. ICM finds somewhat less frequent political discussion among the youth and among likely non-voters, but even among these disaffected groups such conversations will crop up in more weeks than not.

• This article was amended on 24 February 2014. An earlier version said "at the last election 76% of over-65s were still voting, while only 46% aged 18-24 were going to the ballot box". This has been corrected.

ICM Research interviewed an online sample of 2023 adults aged 18+ online on 20-22 December 2013. ICM is a member of the British Polling Council and abides by its rules.