The next election is set to be the most unequal in 60 years thanks to a rising gap in voter turnout based on age, income, class, home ownership and ethnicity, a new study has found.

The Institute for Public Policy Research (IPPR), a centre-left thinktank, found that the turnout gap was negligible between social groups in the 1960s, but that it had grown by 2010 to 18 percentage points between the top set of earners – who are more likely to vote – and the bottom set.

It rises to a 23-point gap between homeowners – who were more likely to vote – and renters, and a 15-point gap between graduates and those who did not go to university. There are 28 points between those aged 61 and over who were more likely to vote than 18-24-year-olds.