Low-income households in Britain are more vulnerable to recession than they were before the financial crisis, the Resolution Foundation has warned, amid the mounting risks of a Brexit downturn.

According to the thinktank, a decade of weak wage growth has left the poorest UK households and middle-income families less prepared for another downturn. It also warned the gradual dismantling of the benefits system under the policy of austerity imposed over the past decade by Conservative-led governments has left people without the same degree of support.

The warning comes ahead of official growth figures for the second quarter, due this Friday, that are expected to show the British economy stalled or slid into contraction for the first time since 2012 during the three months to June.

Two consecutive quarters of contraction are regarded as a recession. The last time the UK suffered a period of falling GDP was during the 2008 financial crisis, which caused the loss of more than 1m jobs as unemployment rose to its highest level since the 1990s.

City economists polled by Reuters expect Friday’s data to reveal zero growth in the second quarter. However, many economists believe GDP will have contracted, including the National Institute of Economic and Social Research. Considered among Britain’s leading thinktanks, NIESR warned that GDP may have fallen by 0.2%.

The warning signals for the economy come after the Bank of England said last week that Britain has a one-in-three chance of plunging into recession at the start of 2020, even if a no-deal Brexit can be avoided.

Threadneedle Street said chronic uncertainty facing British businesses over the future EU trading relationship, as well as slowing international trade volumes due to the US-China trade war, was serving as a handbrake on the economy.

Even if Boris Johnson manages to agree a new Brexit deal with Brussels, it said there was a 33% chance of a recession at the start of 2020. Mark Carney, the Bank’s governor, has said there would be an even worse “instantaneous shock” to growth. He warned that the pound would fall sharply, driving up inflation to further squeeze household spending power.

Should Britain sink into another downturn, the Resolution Foundation warned that poor households would struggle most.

James Smith, research director at the Resolution Foundation, said: “We know from previous downturns that it is lower income households that bear the brunt of economic downturns when it comes to their living standards.

“The global slowdown and continued Brexit uncertainty are making recession preparedness even more urgent. In its response, the government should consider policies that limit and mitigate the effects of the recession, particularly for the most vulnerable in society.”

By analysing household spending patterns over the past decade, the thinktank found that poor families were forced to tighten their belts to a greater extent than the rich in the years that followed the 2008 crash.

While the average fall in spending between 2009 and 2014 was £20 per week, families in the lowest 25% income bracket in Britain focused on buying essentials and cut back over three times more, at £61 a week.

It also said low and middle-income families had yet to recover. Average salaries in Britain have failed to rise above the level recorded before the financial crisis after inflation is taken into account.

Pay growth is on track to complete the weakest decade since the final decade of the Napoleonic wars in the 1810s. Wages fell by £32 a week on average after inflation between 2008 and 2014.

In its analysis, the Resolution Foundation said that a decade of weak wage growth had left poorer households with less scope to cut down on essentials, while a higher proportion than before the last crash had no savings upon which to draw.

Despite some reductions in their debts, as many as 60% of lower income households have nothing to put aside, up by about a quarter since the financial crisis, it said.

The value of benefits relative to average earnings has declined markedly since the financial crisis, and is on course to decline further. Jobseeker’s allowance is set to reach its lowest value ever in 2019-20, at 14.5% of average weekly pay, a fall of 5 percentage points since 2009-10.

The Resolution Foundation said the government needed to take greater steps to prepare Britain for a recession.

“When the next recession hits – as it surely will – there is every chance that it is particularly damaging for those low-to-middle income households that are already close to the edge.

“The policy response will matter, but so too will the action taken ahead of any future downturn,” it warned.