The BBC Trust has ruled that a controversial programme about welfare reforms, written and fronted by the Today presenter John Humphrys, breached its rules on impartiality and accuracy.

The programme The Future of the Welfare State was first broadcast in November 2011 and featured Humphrys going back to his "poor, working-class" birthplace of Splott in the centre of Cardiff, where one in four of the working-age people are on some form of benefit.

The trust, which governs the broadcaster and is chaired by Lord Patten, chided the documentary-makers saying that "judgments reached or observations made are still required to be based on the evidence and should not give the appearance of presenting a personal view on a controversial subject".

The programme, which aired on BBC2 at 9pm, put forward the contentious idea that Britain was going through an "age of entitlement". In it Humphrys interviewed claimants, including a couple on £1,600 of benefits a month who thought "living on benefits an acceptable lifestyle", and welfare experts, from centre-right thinktanks and from the United States, which runs a much tougher public assistance system.

Following a complaint from the Child Poverty Action Group charity and another unnamed individual, the BBC Trust decided the subject met its criteria for being a "controversial subject" and a "major matter". The complaint was decided on by the five-strong editorial standards committee, composed of five BBC trustees.

Significantly the committee found that the programme had not backed up its controversial views with statistics and that this, said the trust, had led to the programme being inaccurate.

In a blunt assessment, the trustees found "the absence of sufficient complementary statistical information to underpin contributors' accounts, viewers were left unable to reach an informed opinion and the accuracy guidelines had been breached".

Specifically the committee said viewers would have concluded that the government was targeting benefits that were responsible for leaving the "welfare state in crisis" and creating the impression that "despite the anecdotal testimonies of jobseekers heard in the programme that there was [a] healthy supply of jobs overall".

"Both issues are central to the viewers' understanding of the key issues discussed in the programme, and because this was a controversial issue… the failure of accuracy had also led to a breach of impartiality."

In considering the case, the committee rejected the claim that Humphrys had presented a personal view, in contravention of guidelines for senior current affairs presenters on controversial issues.

Before the programme was broadcast, Humphrys wrote a personal opinion piece in the Daily Mail to publicise his views and the programme. In it he wrote of "the predictable effect of a dependency culture that has grown steadily over the past years. A sense of entitlement. A sense that the state owes us a living. A sense that not only is it possible to get something for nothing but that we have a right to do so."

Leftwing critics claim the BBC has in recent years hardened its stance on benefit claimants and point out that there has been a welter of countervailing information about the true state of Britain's welfare state.

Laurie Penny writing in the New Statesman complained that the recent BBC1 series Nick and Margaret: We All Pay Your Benefits echoed "the rhetoric of the Department for Work and Pensions, pit[ting] taxpayers against 'shirkers' ."

However in recent weeks, the welfare secretary, Iain Duncan Smith, who used to preface his remarks on Today about benefits with a positive reference to Humphrys' programme, has become exasperated with an apparent leftwing bias of the corporation.

Earlier this month the cabinet minister hit out during a bad-tempered interview with Humphrys on Today over his cap on benefits, accusing Radio 4's flagship programme of using "politically motivated" people to attack his policies. Duncan Smith had the day before been rapped by the official statistics watchdog for misusing benefits cap numbers.

Alison Garnham, chief executive of Child Poverty Action Group, said: "These are major issues of public interest deserving of robust debate and challenging media coverage but which, crucially, also require journalists to speak truth to power, rather than speak untruths about the powerless. If they don't, television audiences and the public at large will continue to be denied the debate they deserve.

"This programme, like too many media stories, failed the public by swallowing wholesale the evidence-free myth of a 'dependency culture' in which unemployment and rising benefit spending is the fault of the unemployed.

"As well as telling the truth about the lack of evidence for the 'dependency culture' narrative, media coverage on social security must give due coverage to important matters like the lack of jobs, poverty pay, zero hour contracts, the high costs of childcare, the high cost of housing and the disappointing performance of the Work Programme."