Inequality in modern Britain is a form of social engineering, and claims that promoting social mobility artificially skews society are nonsense, Nick Clegg is to insist.
Critics who suggest tackling the problem will lead to dumbing down and lower standards have a vested interest in keeping the status quo, the Deputy Prime Minister will tell the Sutton Trust conference on social mobility.
"The myth is that the promotion of social mobility means lowering standards, or somehow dumbing down, to socially engineer a particular outcome," Mr Clegg will say. "This is nonsense. Nonsense, I should add, which is usually peddled by those who benefit from the status quo - and therefore want to keep things the way they are."
He will continue: "Social engineering is what's happening now - the unfairness in our society, and the system that perpetuates it. Social mobility is all about creating a truly level playing field, and a fair race."
Mr Clegg, who attended the prestigious Westminster School, will dismiss critics who suggest his privileged background undermines his ability to tackle the subject.
"I know some people will say I should keep quiet about social mobility, that my birth, my education and my opportunities mean I have no right to speak up," he will say. "I couldn't disagree more. If people like me who have benefited from the system don't speak up, we will never get anywhere."
The London conference will hear that of the one-fifth of children that are on free school meals only one in 100 are Oxbridge entrants, while 70% of high court judges are from a public school background.
Mr Clegg is expected to say: "This is a legacy we cannot afford. 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."
It comes after Labour leader Ed Miliband told the Trust the Government was taking "backward steps" on social mobility by allowing inequality to grow and denying bright youngsters from poor backgrounds the chance to succeed.
He also attacked the "snobbery" that suggests only an academic education is worthwhile, insisting that the UK must give more respect and value to vocational learning and apprenticeships.