Britain risks becoming more divided unless there is a renewed effort to reduce the gap between the "haves and have-nots", the influential Social Mobility Commission has warned.
In a damning report the commission found two decades of government efforts had failed to deliver enough progress and urged ministers to adopt new approaches to tackle the problems in British society.
The commission's chairman Alan Milburn warned "whole tracts of Britain feel left behind" in "volatile and uncertain times".
In an analysis of efforts to bridge the gap between rich and poor under Tony Blair, Gordon Brown, David Cameron and Theresa May, the commission found failings at every stage of a person's life.
Mr Milburn said the country was facing major questions about its future role in the world, national security, the economy and social cohesion.
"As the recent general election seems to demonstrate, there is no consensus in the nation about how best to answer these questions. The public mood is sour, sometimes angry," he said.
"Whole tracts of Britain feel left behind. Whole communities feel the benefits of globalisation have passed them by. Whole sections of society feel they are not getting a fair chance to succeed.
"The growing sense that we have become an us-and-them society is deeply corrosive of our cohesion as a nation."
The commission used a traffic light system to assess progress in improving social mobility at key stages in people's lives, early years, school, training or further/higher education and then into the world of work.
No stage was given a green light, with early years and schools given an amber rating while the later "young people" and "working lives" stages received a red rating.
Overall, only seven policies scored a green, with 14 ambers and 16 reds.
The report found:
:: At current rates of progress it will take about 15 years before all children are school ready by the age of five and 40 years before the attainment gap between rich and poor at that age is closed.
:: There is currently no prospect of the gap between poorer and wealthier children being eliminated at either GCSE or A-level, which Mr Milburn said was "totally unacceptable".
:: In higher education, it will take about 80 years before the participation gap between students from rich and poor areas closes.
:: One-in-five people are struck on low pay, a consistently higher proportion than in similar nations.
:: There is "currently no prospect of the Government achieving its ambition of Britain becoming a high-skilled, high-paying economy".
:: Economic growth in London and other cities has left parts of England behind and at risk of being "hollowed out" as people leave in search of opportunities.
:: The income and wealth divide has become "more acute", between 1997 and 2017 the bottom fifth of households saw incomes increase by just over £10 a week compared with £300 for the top fifth.
:: A new generational divide has emerged with growing inequality between the old and young, who are more reliant than ever on their parents for help to buy homes.
Former Labour minister Mr Milburn said: "Our country has reached an inflection point.
"If we go on as we have been, the divisions that have opened up in British society are likely to widen, not narrow.
"There is a growing sense in the nation that these divisions are not sustainable, socially, economically or politically. There is a hunger for change.
"The policies of the past have brought some progress, but many are no longer fit for purpose in our changing world."
The commission recommended that the Prime Minister should put in place a single cross-government plan to deliver the social mobility agenda, with 10-year targets to halt the short-term nature of many interventions.
A social mobility test should be applied to all new public policy and every Budget should identify how taxpayers' money is being redistributed to address geographical, wealth and generational divides.
The commission said the Prime Minister should "abandon plans to extend grammar schools" and instead focus on new collaborative approaches to turning around failing schools.
The Government has already reined in its plans for a new generations of grammars following the general election, with the Queen's Speech promising only to work with Parliament to bring forward proposals for school improvement "that can command a majority".
A Department for Education spokesman said: "Tackling social mobility is at the heart of the government's ambition to make Britain a country that works for everyone.
"There are 1.8 million more pupils in good or outstanding schools than in 2010, and we are delivering three million apprenticeship places, opening up access to our higher education system and investing £500 million a year into technical education.
"However, we know that more must be done, and that's why last year we launched our £72 million Opportunity Areas programme. This is bringing together local businesses, schools and councils in 12 social mobility 'coldspots' to create better opportunities for young people."
Save the Children chief executive Kevin Watkins said the Government should make the quality of nursery education a top priority.
He said: "It's nothing short of a scandal that in this day and age, so many of our children are falling behind in their learning from the start and left to stay behind throughout their lives.
"We all know that unless we get education right in the early years of a child's life, so many of them - especially the poorest - will struggle right through to their GCSEs and beyond, into the world of work and even in their relationships."