After the anti-war marchers took to London's streets in February 2003, Tony Blair brushed them aside and suggested history would be his judge. Ten years on, the ink on the first draft of history is dry, and, according to a Guardian/ICM poll, Britons are not reading it in the way Blair would have hoped.

A majority of voters, 55%, agree with suggestions that "the London marchers were right", because "a war sold on a false prospectus delivered little but bloodshed". That is almost twice the 28% who believe the marchers were wrong, on the basis that the war's achievement in "toppling the dictatorship of Saddam Hussein" eventually made the world a better place.

The approximately two-to-one balance of opinion against the Iraq war broadly applies across both sexes and every age range. Every nation and region of the UK also retains a clear anti-war majority, with the judgment in Wales – 65% in favour; 22% against – the most emphatic.

The marchers are also vindicated by opinion up and down the social scale, although the 49%-36% balance of opinion in favour of the marchers among the so-called AB occupational grades is somewhat more balanced than the crushing anti-war majorities among working-class voters.

The parliamentary votes on Iraq in 2003 split the Labour party down the middle, with 139 rebels on the final Commons vote, whereas, despite 15 Conservative dissenters, the great bulk of Tory MPs came together to support the invasion.

Ten years on, there is no partisan slant in the public's opposition to the war. Conservative supporters believe the marchers were right by a 57%-30% margin, statistically indistinguishable to the 57%-29% support for the marchers found among Labour voters. Supporters of the Liberal Democrats, the only big party in 2003 to offer a united anti-war stance, are only marginally more strongly behind the marchers – they are split 59%-24%. The 54%-33% anti-war majority found among Ukip supporters confirms Blair is judged to have been on the wrong side of history, right across the political spectrum.

The public was sceptical about the Iraq war in advance, and the marchers claimed to speak for the country, but what is often forgotten is that by the eve of hostilities, on 20 March 2003, a more belligerent mood was taking hold.

More than 20 polls were carried out between 18 March and September 2003, and every one found a plurality supporting the war. Subsequently, as the debate turned to missing weapons of mass destruction, abused intelligence and Iraq's developing civil war that opinion swung firmly against Blair.

It is several years since the last proper poll on the Iraq war, but by 2007, when the last surveys were done, opinion had hardened into the same sort of anti-war majority confirmed by the latest ICM survey. In June 2007, for instance, YouGov found a 55%-30% anti-war majority.

Blair had hoped success in Iraq would consolidate support for the broader agenda of "liberal interventionism", which he put forward in his Chicago speech at the height of the Balkan crisis in 1999. But after Iraq came to be seen as a mistake, things could easily have gone the other way, with voters fearing further military intervention would reap the same sort of chaos.

A decade on, the poll finds Iraq remains a special case, with Britain split on the wider question of armed intervention.

The survey reminded respondents of other controversial engagements, in Afghanistan, Libya and Mali, but found the 48% who believe "military interventions solve little, create enemies and generally do more harm than good" are only three points ahead of the 45% who believe that "through its armed forces, Britain generally acts as a force for good in the world".

Conservative voters feel slightly more warmly about the troops than others – 53% of them regard interventions as a force for good – but with 47% of Labour and 45% of Lib Dem voters in agreement, the differences are not especially large. Supporters of Ukip are especially anti-intervention, believing by 56%-32% that it does more harm than good, suggesting they are more Little England than imperialist nostalgics. That introverted mood on the political right is only one political consequence of what voters now judge as Blair's failure in Iraq.

ICM Research interviewed a random sample of 1,001 adults aged 18 and over by telephone on 8-10 February 2013. Interviews were conducted across the country and the results have been weighted to the profile of all adults. ICM is a member of the British Polling Council and abides by its rules.