The state education system is "dangerously lop-sided" and fails to teach children the social and workplace skills they need for their future, according to a university leader.
Sir Anthony Seldon, vice-chancellor of the independent Buckingham University, said pupils educated at fee-paying schools still dominate the top positions in British life as they are more likely to learn vital "soft" skills such as teamwork, leadership and character.
His comments come after research found the UK is still overwhelmingly run by privately educated Oxbridge graduates who dominate professions including politics, journalism, the military and the law.
Giving the first inaugural CIFE (Council for Independent Education) lecture in central London, Sir Anthony will say: "Success at GCSE and A-level exams and at national and PISA (Programme for International Student Assessment) league tables is a necessary but not a sufficient condition for a good education system. The country no longer just needs, if it ever did, people who just get good exam results, but nothing else.
"For years now, our policy-makers and education establishment have become so drunk on imbibing PISA and exam tonic that they have come to believe that league tables are all education is.
"Study after study, and most recently, David Deming at Harvard, shows that the 21st century workplace does not just need those who excel at memory and exam skills that computers can do far better, but rather those human and entrepreneurial skills that the children at state schools are rarely taught and many will never learn.
"The terrible truth is dawning that the whole focus of the national state system remains irredeemably 20th century and dangerously lop-sided. It is narrow, dull and too repetitive to engage the active intellect and interest of many students and teachers.
"It is not surprising that so many teachers are fleeing abroad and that students from independent schools continue to dominate so many of the major positions in national life."
He adds: "A strong, vital and healthy independent education system at school and higher education level, acting as a competitor, challenger and irritant to the state sector, is absolutely vital for the country.
"The boons of the private sector have been long-trumpeted. Less discussed is the breadth of its education in the soft skills of entrepreneurship, independent thinking, teamwork, leadership and character, which come from its broad arts, sports and service programmes, as well as the systematic engagement undertaken by schools with parents and alumni to create a support network for pupils while at school, and after leaving."
A Department for Education spokeswoman said: "We have placed high expectations at the heart of our schools, with a rigorous new curriculum that focuses on the knowledge and skills most valued by employers, world-class exams and an accountability system that rewards those schools which help every child to achieve their best.
"Character education and academic attainment are not mutually exclusive - they are two sides of the same coin. We encourage schools to develop pupils who are confident, motivated and resilient, and who will get on better in both education and employment.
"That's why we are investing £5 million in character education to help pupils develop the resilience they need to succeed in school and later life, while giving teachers the freedom to develop lessons that will excite and inspire their pupils."