A study by the Social Mobility and Child Poverty Commission also found that 54 percent of the nation's "top 100 media professionals" attended private schools (as opposed to 7 percent of the population as a whole).
This top-100 list comprises editors, columnists and broadcasters and contains a higher proportion of those with a privileged private education than it did 28 years ago (when they were said to be 47 per cent of the total).
Some 26 percent of this group attended grammar schools, compared with 16 percent who attended comprehensives - the other 4 percent went to international schools. And 45 percent graduated from Oxbridge.
The study also looked into the backgrounds of 261 newspaper columnists. Some 43 percent attended independent schools compared with 23 percent who went to comprehensives (with most of the remainder educated at grammar schools or internationally). Nearly half (47 percent) attended either Oxford or Cambridge universities.
It also broke these figures down into tabloid and broadsheet columnists, finding that more broadsheet columnists (25 percent) attended comprehensive (“or secondary modern school”) than tabloid columnists (20 per cent).
But a higher proportion of broadsheet columnists (45 percent compared with 38 percent) attended independent schools. Some 57 percent of broadsheet columnists attended Oxbridge, and 78 per cent went to one of the Russell Group of 24 leading universities.
One in four (25 percent) tabloid columnists attended Oxbridge and 49 percent went to a Russell Group institution.
Three quarters (74 percent) of the top-100 list attended Russell Group universities (which includes Oxbridge), compared with 68 percent of columnists.
But a higher proportion of broadsheet columnists (45 percent compared with 38 percent) attended independent schools. Some 57 percent of broadsheet columnists attended Oxbridge, and 78 percent were at Russell Group universities.
Three quarters (74 percent) of the top 100 list of media elite attended Russell Group universities (which includes Oxbridge), compared with 68 percent of columnists.
The research, which also looked at politics, the public sector and business people, showed that the number of people in the media ‘top 100’ who attended university has risen from 78 percent in 1986 to 81 percent in 2006 and now 90 percent in 2014.
The number of people in this group to have graduated from Oxbridge has decreased from 52 percent to 45 percent since 1986, but more went to one of the universities judged by the Sutton Trust to be in the top 13 – from 59 percent to 62 percent.
The report found that the ‘top 100’ appears to be “slightly more dominated by those from independent school backgrounds” since 1986. Then, 47 per cent attended independent schools, compared with 54 percent now.
The study also researched 187 BBC executives. A quarter (26 percent) attended private schools, and 37 percent comprehensive. A third (33 per cent), meanwhile, graduated from Oxbridge, and 62 percent attended Russell Group universities.
Overall, the study analysed the backgrounds of more than 4,000 individuals holding top jobs in British society.
It concludes that Britain's elite is still "formed on the playing fields of independent schools" and "finished in Oxbridge's dreaming spires".
More than seven in ten (71 percent) of senior judges, 62 percent of senior armed forces officers, over half of permanent secretaries (55 percent) - the most senior civil servants in government - 53 percent of senior diplomats, 45 percent of public body chairs, 44 percent of the Sunday Times Rich List, 35 percent of national rugby teams and a third (33 percent) of the England cricket team attended a fee-paying school, the study found.
Former private school pupils are also over-represented in politics, with half of the House of Lords attending an independent school along with over a third (36 percent) of the Cabinet, a third (33 percent) of MPs, and 22 percent of the shadow cabinet.
Alan Milburn, the commission's chair, said: "This research highlights a dramatic over-representation of those educated at independent schools and Oxbridge across the institutions that have such a profound influence on what happens in our country. It suggests that Britain is deeply elitist."
He added: "Locking out a diversity of talents and experiences makes Britain's leading institutions less informed, less representative and, ultimately, less credible than they should be.
"Where institutions rely on too narrow a range of people from too narrow a range of backgrounds with too narrow a range of experiences they risk behaving in ways and focusing on issues that are of salience only to a minority but not the majority in society.
"Our research shows it is entirely possible for politicians to rely on advisers to advise, civil servants to devise policy solutions and journalists to report on their actions having all studied the same courses at the same universities, having read the same books, heard the same lectures and even being taught by the same tutors.
"This risks narrowing the conduct of public life to a small few, who are very familiar with each other but far less familiar with the day-to-day challenges facing ordinary people in the country."
Milburn said there is a risk that the more just a few dominate key roles in society, the less likely it is that others think they can take part, leading to a "closed shop at the top".
The study says the data suggests that the "grip" of the narrow social group that are currently in the top jobs will only loosen slowly in the future and calls for a national effort involving government, parents, schools, universities and employers to "break open" Britain's elite.
* William Turvill reports for Press Gazette.com .