A growing gap in voter turnout across income, education and homeownership combined with the role of donations in politics has put the next election on course to be the most unequal in six decades, a think tank report has claimed.

A report from the Institute for Public Policy Research (IPPR) has concluded that people in the UK are “not politically equal” and that the democratic principle of “one person, one vote” does “not hold true”.

The IPPR said the UK risks entering a “doom loop” where policy is becoming less responsive to citizens and so further undermines faith in democracy.

There are real differences in who gets their way in our democracy

In the 1960s, the turnout gap at general elections between social groups was “negligible”, according to the IPPR report titled Who Decides? Influence and Inequality in British Democracy.

“By the 2010s, it had grown to 18% between the top and bottom third of earners; to 23% between renters and homeowners; to 15% between those who did and did not attend university; and to 28% between those who are 61 or older and 18-24 year-olds,” the IPPR said.

The bottom third of earners are also around three times more likely to say it is not worth voting than the top third, with similar differences found between those with and without university degrees, the think tank said, while renters are more than twice as likely as homeowners to say it is not worth voting.

University graduates are also more likely to contact a politician and join protests, the report found.

Inequalities can also be seen in political donations and the backgrounds of those who become MPs, the think tank said.

People in this country are not politically equal. Put differently, the democratic principle of ‘one person, one vote’ does not hold true

The share of party donations coming from those donating more than £100,000 has grown by around 8% over the past decade, the IPPR said, and the number of MPs entering parliament from working-class jobs has fallen twice as quickly as the share of the public working in similar jobs.

The report concluded: “People in this country are not politically equal. Put differently, the democratic principle of ‘one person, one vote’ does not hold true.

“Inequalities in power and influence are generated and reinforced across the policymaking process.

“This is at the heart of explaining the growth in economic inequality, the erosion of trust in the competence and fairness of democratic government and the rise of populism.

“Despite that, political inequality remains a blind spot for progressives.”

No matter who’s in power, our democratic machine needs rewiring

Senior research fellow at IPPR Dr Parth Patel, said: “For the first time since the birth of democracy in this country, people do not expect their children to be better off than them.

“In the face of insecurity, people naturally want control – to take back control of a political process that has allowed wages to fall after flatlining for a decade, and locked generations out of owning a home.

“There are real differences in who gets their way in our democracy. Policy is more responsive to preferences of the well-heeled than of the worse off, and people know this – but it seems to be a blind spot for most politicians.

“No matter who’s in power, our democratic machine needs rewiring. If people are once again to be authors of their own lives and to feel secure, they must sense their influence in the collective decision-making endeavour that is democracy.”