Establishment figures should stop sneering at northern England’s Brexit voters and instead work to understand their concerns, a leading thinktank will warn on Friday.

Speaking at its annual State of the North conference in Leeds, the director of the Institute for Public Policy Research (IPPR) North, Ed Cox, will argue that Brexit negotiations should focus on the needs of the areas that voted most strongly to leave the EU.

“In June, the people spoke. But in the north, they shouted,” he will say. “It has made me very angry that since the referendum, when it has become clear that the northern economy could suffer significantly as a result of the Brexit decision, that some in the metropolitan media have presented northerners as foolish or simple.

“We believe that Brexit is a cry of community outrage at the imbalances of wealth and power, played out in glorious technicolour within and between the regions of this nation. Scotland had already had its say, in June it was a chance for England to rise up against the wishes of the Westminster elite.”

The thinktank’s report State of the North 2016 – described as an annual health check on the northern economy – finds that the parts of the north that voted most strongly to leave the EU are also the most vulnerable to the economic turbulence caused by Brexit.

The study finds that Humber (which voted 65% to leave), Tees Valley (64%), and the Sheffield city-region (62%) had the highest percent of leave votes in the north of England, but are also the areas that have yet to transition fully from their industrial pasts.

Cox will say that London is more insulated from the impact of Brexit than the north of England, as northern regions are more than twice as dependent on EU trade as the capital.

The report urges the government to establish a northern Brexit negotiating committee so that the concerns of the region are heard during Brexit negotiations and argues for more attention to be paid to the areas that voted leave in June as well as the big cities of the north.

Whereas the north’s biggest cities voted to remain on similar levels to London and Scotland – 61% of people in the city of Manchester voted to stay – the surrounding areas voted to leave, suggesting people in those areas have not felt the benefits of the ”northern powerhouse” project.

The report makes the case for EU powers to be passed from the European level to communities and regions. “To conclude that the north’s vote to leave was an act of collective self-harm is to completely misunderstand what it is to be northern,” Cox will say, arguing that the north of England has “a rich history and tradition of taking back control”.

“In simple terms, just like our Scottish neighbours, northerners have historically compromised short-term economic benefits for the sake of their wider freedom and autonomy. This I believe is what we are witnessing in the Brexit vote. The 80-year experiment with centralisation is over and it is little wonder the establishment are struggling to get it.”

Giving the keynote speech at Friday’s conference, Andy Burnham, the former shadow home secretary and Labour’s candidate for mayor of Greater Manchester, will say that the Brexit vote was “a cry for change” from some of the most forgotten towns in the UK.

“There is an idea that voters in the north were thick, xenophobic or they didn’t understand their vote. I know from my own constituency that is absolutely not the case. What people were calling for was fairness,” he will say.

“The sneering tone from some commentators shows that there is a kind of elite in politics and the media that hasn’t listened to these voters for many years. There’s a feeling in some former industrial communities that free movement has been used by big companies to move people around like a commodity, driving down peoples wages.”

Julia Unwin, the chief executive of the Joseph Rowntree Foundation, said IPPR North’s report was a powerful reminder that swaths of the country had not shared in the country’s growth and had been left vulnerable to economic shocks.

“While many northern cities have been a success story over the past decade, their revival has not spread beyond many city centres. That has to change,” she said. “We need a post-Brexit settlement for northern towns that have been left behind. The northern powerhouse is a welcome attempt to rebalance the economy, but this needs to work for all of the north.”