Children from affluent families are more than three times more likely to go to a top university than their working class peers, a new study shows.

The research by Dr John Jerrim, of the University of London’s Institute of Education, reveals children whose parents are professionals are 3.2 times more likely to attend Russell Group universities.

The findings are mirrored by similar proportions of students going on to the most selective public universities in the US and Australia.

The study also concludes that the difference between the academic routes taken by children of white- and blue-collar workers cannot be simply explained by the gap in attainment levels. In England, 27 per cent of the gulf is not related to exam grades, it argues, with the figure rising to 50 per cent in Australia.

At elite private US universities such as Yale and Harvard, the gap is even larger: children with “professional” parents are a massive six times more likely to attend, and 52 per cent of this gulf cannot be explained by academic achievement.

“Although academic achievement is an important factor, a substantial proportion of the elite university access gap in each country remains unexplained,” Dr Jerrim will tell the Sutton Trust’s advancing access and admissions summit today. “This suggests that there are working class children who, even though they have the grades to attend, choose to enter a non-selective institution instead.”

The research also reveals that students from poorer homes account for just one in 20 undergraduates at leading universities in the UK and the US.

Sutton Trust chairman Sir Peter Lampl said: “This new research confirms that there many able children either not applying or not being admitted to the best universities, and this is true internationally.”

The event, hosted by the Royal Society in London, will be opened by business secretary Vince Cable, and attended by around 80 academics and university admissions leaders from leading universities such as Harvard, Yale, MIT, Oxford and Cambridge.