Analysis by Royal London of government’s family resources survey data for 2013-14 – the most recent full set of figures the researchers had available to them – showed 5.5m working adults across the UK would not be eligible for full housing benefit should they lose their job, more than double than in 2003-04 and the majority of who are living in London.
Those who are particularly vulnerable include couples who can afford their rent between them but would struggle on one set of wages, people who are deemed to have spare bedrooms for the purposes of the benefit rules and those who are living in more desirable parts of town.
Meanwhile, those aged between 25 and 34 were most likely to be left without a home should the worst happen, with Royal London predicting as many as 511,000 in this age bracket could find themselves without access to the necessary housing benefit to cover their rent.
"Rising unemployment and a surge in the number of private renters could create a toxic cocktail where working renters discover to their cost that there are large gaps in the housing benefit safety net," said Steve Webb, director of policy at Royal London. "This report shows that the benefits system would not meet the rent of the majority of working renters."
Debbie Kennedy, head of protection at Royal London, added: "In an era where private renting is growing so rapidly, we need to ensure that renters are better prepared for such eventualities."
Figures released by the Office for National Statistics last month showed renting was on the rise, with one in five (19.6 per cent) of households renting in 2015, compared with 10.3 per cent in 2005.