There is a "stark gap" between the life chances of the poorest and the better-off in Britain, the Government will admit today, as it publishes alarming research that reveals how wide that gulf is.

The study, to be unveiled by Nick Clegg, shows that:

l One child in five is on free school meals, but only one in 100 Oxbridge entrants is.

l Only 7 per cent of children attend private schools, but these schools provide 70 per cent of High Court judges and 54 per cent of FTSE 100 chief executives.

l One in five children from poorer homes achieves five good GCSEs, compared with three out of four from affluent homes.

In response to the findings, Mr Clegg will take a political gamble by publishing new benchmarks so the public can track whether the Government is delivering its pledge to improve social mobility. Ministers admit they are making a rod for their own backs.

In a speech to the Sutton Trust, Mr Clegg will admit that the Coalition "cannot afford" to leave a legacy like the current position. "Morally, economically, socially: whatever your justification, the price is too high to pay. We must create a more dynamic society. One where what matters most is the person you become, not the person you were born," he will say.

The strategy document will admit: "No one should be prevented from fulfilling their potential by the circumstances of their birth. What ought to count is how hard you work and the skills and talents you possess, not the school you went to or the jobs your parents did.

"The UK is still a long way from achieving this ideal. Income and social class background have a significant impact on a child's future life chances and there have been few signs of improvement in recent decades."

The Deputy Prime Minister, educated at the private Westminster School and Cambridge University, will insist he is the right person to champion social mobility. "I was lucky. But it should not be a question of luck. It is my strongest political conviction that if we have a chance to change the way our society works, if we have a chance to open up success to all, we must seize it," he will say.

Mr Clegg will dismiss "the myth that the promotion of social mobility means lowering standards, or somehow dumbing down, to socially engineer a particular outcome. This is nonsense ... which is usually peddled by those who benefit from the status quo – and therefore want to keep things the way they are."

The Liberal Democrat leader will insist the problem can be tackled in an age of austerity and reject the idea that the solution is to redistribute income. Other factors include the education system, the housing market and possibly social attitudes, Mr Clegg will argue, so the Coalition is focusing on closing educational attainment gaps and improving early years education.

He will announce that the Government will be the first in the world to publish 17 annual "trackers" including:

l The proportion of children on free school meals achieving grades A* to C in English and maths at GCSE.

l Participation by 18- to 24-year-olds in full-time education by social background.

l The proportion of children achieving at least grades AAB at A-level by types of school or college attended.

But Ed Miliband, the Labour leader, warned the Government could not improve social mobility without tackling inequality. He said: "If you are born poor in a more equal society like Finland, Norway or Denmark then you have a better chance of moving into a good job than if you are born poor in the United States. If you want the American Dream – go to Finland. This isn't surprising. It's harder to climb the ladder when the rungs are further apart."

A Church of England charity described England as one of the most unequal countries in the Western world as research showed an "alarming disparity" between the richest and poorest neighbourhoods. Nine out of 10 of the poorest communities – five of them in Liverpool – are in the North-west of England with the 10th in Middlesbrough in the North-east, the Church Urban Fund discovered.

Only two of the top 10 least-deprived communities are in the North of England – Wheldrake, York, and Alderley Edge, Cheshire, with Camberley Heatherside, Surrey, heading the list of the least-deprived.

University test: two who aimed for something better

Georgina Jones, 23, Peckham: "So many can't break the chain. A lot see university as for rich white kids"

She achieved A*s and As at GCSE and A-level and studied Law at Nottingham, the first person in her family to go to university. With support from the Social Mobility Foundation she earned a training contract at an international law firm.

"I live in Peckham with my mum, brother and sister. We've always been a normal working class family. My father passed away when I was 13 and my mum got into quite a lot of debt. I went to the local comprehensive and I always knew I wanted to get out of Peckham – I didn't want the same sort of lifestyle that I saw some of the people around me getting into. Guys I went to school with ended up in prison. Girls were having children at 15. People would always say that middle-class life and middle-class job belonged to another world. My dream was to go to Oxford but people told me that I wouldn't because of my postcode – that people like us didn't go to Oxford.

"I was really ambitious. I got good GCSEs and A-levels and got a place to study Law at Nottingham. But it isn't like that for everyone. I feel like my peers are being held back. Teachers would just say get 5 A*-Cs. There was very little guidance that the good universities wanted higher grades in more traditional subjects. So many people can't break the chain. A lot of people saw university as being for rich white kids – they'd cross off university and all the careers associated with it.

"Schools are the crucial thing. For people that need a bit of support we need smaller classes and more peer support in schools."

Liridon Sylisufi, 19, Dagenham, east London: "The first barrier you meet is a lack of understanding that there is more out there"

"I was born in Albania and arrived in the UK aged 5. I was in school mostly in Newham and then moved to a secondary school in Barking and Dagenham. It was me, my mum and my little brother at home and I was on free school meals.

"When it came to Sixth Form there was a lot of pressure on me to get work, which I did 20 hours a week in Argos. It was hard to fit my studies in around that. There were seven in my friendship group and only two of us went on to Sixth Form.

"In Newham the first barrier you meet is a lack of understanding that there is more out there. You don't get a lot of people that have been to the top universities from schools like mine. I was the first person to get into Oxbridge from my Sixth Form. It's not that people aren't able to do it – they're not pushed to apply."