Poor, bright children are about a third less likely to earn a high wage than their rich, less clever counterparts, according to Education Secretary Justine Greening.

Speaking on Thursday at the Social Mobility Commission conference, she explained that research has shown that when they grow up, disadvantaged children earn over £2,000 less a year than those who are more privileged.

"Children from high-income backgrounds who show signs of low academic ability at age five, are 35% more likely to become high earners than their poorer peers who show early signs of high ability," Greening said, according to the FT.

She added that even if children have the same education, the same experience, and the same job, if they were born to professional or managerial parents, the difference was still clear.

She also said children in the most disadvantaged areas of the country are 27 times more likely to go to an inadequate school than those in more advantaged areas.

The figures come from research conducted in 2015 by the London School of Economics for the Social Mobility and Child Poverty Commission. The study looked at the impact social background had on the wages of people at the age of 42, revealing that social background and family income both had a significant effect on the likelihood of becoming a high earner.

Effectively, the researchers concluded that better-off, middle-class parents are more successful in creating a "glass floor," which protects their children from moving down the social scale. In turn, this makes it harder for smart children from less privileged backgrounds to move up.

The study came up with two main channels better-off parents use to keep this "glass floor" in place. Firstly, they can help their children secure education and job opportunities because they have more money to do so. This means these children are more likely to receive better careers advice and guidance, and learn important skills such as self-confidence, decisiveness, and leadership.

Secondly, better-off families can help their children informally through their own social networks, such as assisting in getting them internships. It's the old case of "It's all about who you know, not what you know."

"It’s a social scandal that all too often demography is still destiny in Britain," said Alan Milburn, chair of the commission, when the research was released. "The government should make its core mission the levelling of the playing field so that every child in the country has an equal opportunity to go as far as their abilities can take them."

According to Greening, grammar schools are part of the answer to this problem, because they give non-wealthy but clever children the chance to get a better education than their parents could otherwise afford. However, a main criticism of grammar schools is that richer families can afford tutors for their children to get them to pass the tests, effectively keeping this glass floor in place.

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