Theresa May has dismissed many of the findings of the Guardian/LSE Reading the Riots study – the largest set of interviews with people who took part in England's summer unrest – arguing those involved in the trouble were an "unruly mob" who were "thieving, pure and simple".

But a report from charity the Children's Society, which surveyed 13 to 17-year-olds and adults, has found that young people across the UK believe poverty is one of the key reasons behind the August riots. Of those questioned, 66% of adults and 57% of children believed people had rioted "to get goods and possessions they couldn't afford to buy", according to the survey of 1,004 adults and 1,027 children.

Writing in the Mail on Sunday, the home secretary said the riots were not about "protest, unemployment or cuts. They weren't about the future, about tomorrow and a person's place in the world. They were about today, about now. They were about instant gratification."

Enver Solomon, policy director at the Children's Society, said that a perceived sense of "material deprivation" could not be overlooked as a factor behind the riots. "This research shows that Theresa May is out of step with the majority of children and adults in this country when she says the riots were about instant gratification," he said. "Most people believe that the riots were caused by a whole range of factors – and poverty and material disadvantage are at the heart of it."

Analysis of more than 1,000 court records suggests 59% of the England rioters come from the most deprived 20% of areas in the UK. Analysis by the Department for Education and the Ministry of Justice of young riot defendants found 64% came from the poorest fifth of areas and only 3% from the richest fifth.

The Guardian/LSE Reading the Riots report – which interviewed 270 people involved in the riots – found that opportunism played a role in the riots when a "suspension of normal rules presented them with an opportunity to acquire goods and luxury items they could not ordinarily afford".

But rioters also identified a number of other motivating grievances, "from the increase in tuition fees, to the closure of youth services and the scrapping of the education maintenance allowance", according to the report.

Only 7% of adults and 5% of children interviewed in the Children's Society report, Behind the Riots, believed anger at cuts had played a significant part in the riots. But 29% of 17-year-olds cited cuts as a reason behind the unrest, with 67% of those saying more government support was needed following the riots.

"The prospects of this age group are pretty bleak," said Solomon. "They felt particularly cuts to public services, they are facing great uncertainty and are particularly effected by high youth unemployment levels." One young person interviewed as part of the report stated: "Young people aren't being prioritised … the government needs to listen."

The report found one in five (19%) of children and 23% of adults believed people had taken part "just for fun".

Many children and young people felt perception of them had deteriorated since the riots, with 20% feeling they were viewed more negatively. "Our findings show that there is agreement between adults and children that the government should be providing more support to young people," said Solomon.

"This sends a clear message to central and local government that the public would like to see more positive activities on offer to children rather than a reduction in out-of-school youth provision. With the considerable challenges now facing children and young people in early adulthood, the case for investing in youth support must be taken seriously."

In the comment article, May did not reiterate the initial government line following the unrest that gangs had been at the centre of the riots. Reading the Riots found that the role of gangs had been overstated and gang members that were involved had behaved in an entirely atypical manner for the duration of the riots, temporarily suspending hostilities with postcode rivals.

But she emphasised the fact that nearly two-thirds of those brought before the courts were charged with burglary, robbery or theft. "So we know that, actually, they weren't trying to make any political or social statement; they were thieving, pure and simple," she wrote.

Reading the Riots found that widespread anger and frustration at people's treatment at the hands of police was significant, with 85% said policing was an "important" or "very important" factor "which was felt to be unfairly targeted and often undertaken in an aggressive and discourteous manner".

May said: "On average each rioter charged had committed 11 previous offences. In other words, they were career criminals. Naturally, they don't like the police and I'm glad they feel upset by them. One rioter interviewed by the academics said the police are always 'causing us hell'. In my role as home secretary, I can only say: 'Good.'"

May implied the Guardian/LSE report was useful because it was "important as it is to hear [rioters] views – no matter how appalling we may find them", but she stressed that it was "just as important to focus on those who didn't take part", such as victims of the violence.

Solomon said: "Yes we must listen to victims, but we must also listen to young people. We can't just dismiss people who don't fit into a government narrative. The government must look at a variety of views and consider a response. The riots were not simply about lawlessness, it was more complex than that."