Nick Clegg has vowed to address the "absolute scandal" of Britain's lack of social mobility and open up a society that is "too closed" and "too static".

As the government publishes 17 trackers to assess progress in improving life chances over the coming decades, the deputy prime minister will tackle what aides describe as "narrow egalitarianism" on the left and "laissez-faire shoulder-shrugging" on the right.

He told ITV's Daybreak: "One of the things we are doing in these figures that we are publishing today – for the first time ever, it has never been done before – we are lifting a lid, if you like, on an absolute scandal, which is that, in our country more than many other countries, where you are born and certainly what your background is seems to determine your subsequent life."

Although he conceded that change could not be achieved overnight, Clegg said social mobility had to be factored into the education system, from pre-school to university.

He told Sky News that while the coalition was not launching an attack on the middle classes, "it's just not right that if you go into an average classroom, one in five children will be on free school meals. Go into an Oxford or Cambridge lecture theatre and only one in 100 will [have been] on free school meals."

It was, he added, a "national scandal" that some of the country's brightest children were being left behind simply because they came from poorer backgrounds.

Clegg also stressed the need for universities to think carefully about student admissions. Speaking on BBC Radio 5 Live, he said they had "to look behind the grades an applicant has on their CV and look at the potential a youngster has to thrive at university".

While viewed with suspicion by some in the UK, he added, such an approach was "totally uncontroversial" in the US and elsewhere.

In a speech on Tuesday morning that is likely to anger some Tories, Clegg will dismiss claims that widening university access is a "dangerous piece of revolutionary socialism".

"It may surprise the non-Brits among you to learn that in some quarters, the idea of carefully taking into account the impact of background in assessing university applications has been painted by some as a dangerous piece of revolutionary socialism," Clegg will tell a Sutton Trust conference in London.

"But far from dumbing down, it's about increasing opportunity to achieve excellence."

Clegg's criticism of the Tories is the final of three "myths" about social mobility he says are promoted by critics on the left and right. The myths are:

• The belief among some on the left that the government should focus solely on tackling income inequality between the rich and poor because social mobility will "follow automatically in the wake of greater equality". Clegg has in mind an article in the Guardian last week by Kate Pickett and Richard Wilkinson who argued that "reducing income inequality is the most important step" towards giving children equal opportunities in life.

Clegg will say: "Of course, reducing inequality is a good and laudable aim. But unfortunately it's not the straightforward route to social mobility that its proponents suggest."

The deputy prime minister will cite Australia and Canada, which have similar levels of inequality to the UK while enjoying Scandinavian levels of mobility. "So there must be other things going on here. In the education system; in the housing market; or perhaps in social attitudes. Factors impacting on mobility that closing the income gap will not, and cannot, address."

• The belief among some on the right that social mobility can only be tackled during periods of strong economic growth.

"A growing economy will often do a good job of increasing absolute social mobility – simply by making everyone better off than the previous generation. But growth does not necessarily improve relative social mobility, in other words the way your background affects your life chances," he will say. "It is worth noting that during the long economic upturn from the mid-90s to the financial crash, social mobility rates remained flat."

• The belief among some on the right that rules which allow universities to take into account a student's social background will penalise those educated in the private system. Clegg will say: "There is compelling evidence that translation of ability into attainment is affected by your social and educational background." He will challenge critics who say he should not talk about social mobility because of his privileged background – he was educated at Westminster, one of Britain's most expensive private schools, and Cambridge University.

"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. I couldn't disagree more. If people like me who have benefited from the system don't speak up, we will never get anywhere.

"We have to fight for a society where the fortunes of birth and background weigh less heavily on prospects and opportunities for the future. I was lucky. But it should not be a question of luck."

Aides said Clegg was prepared to receive a "bloody nose" by challenging elites that want to block access out of a sense of entitlement. "Nick is bloody-minded about this. He is taking on vested interests but if you are not prepared to do that what is the point of being a liberal? He is also challenging the narrow egalitarianism of some on the left and the laissez-faire shoulder-shrugging of some on the right."

The deputy prime minister will use the conference to publish a report setting out 17 measures of social mobility through life. These include school readiness, the proportion of children on free school meals achieving a "good level of development"; and the social backgrounds of pupils at 19 who achieve the AAB grades at A-level demanded by the Russell Group of universities. Clegg will make clear that progress will be slow. "We hope to see some change in the coming years," one source said. "But this will take decades."