The sharp achievement gap between state and private school-educated pupils means there is a "shocking waste of potential", according to the chairman of educational charity the Sutton Trust.
Sir Peter Lampl's remarks come in the foreword to a new report that shows private school pupils will earn significantly more than their state school peers.
"This is a shocking waste of potential. This report clearly sets out the advantages that can be gained from a good private education," Sir Peter writes.
The Sutton Trust is calling for more independent schools to take on able pupils from less well-off backgrounds.
The charity suggests private schools should get the same funding per pupil as state schools, with the ability to charges fees on a means-tested basis, with the poorest paying nothing.
Their study suggests extending such a scheme to 100 leading private schools would cost the Government about £215 million a year.