Nearly a third of candidates standing for parliament at the next general election has been privately schooled - compared to 7% of the UK population.
A study by the Sutton Trust found 31% of new candidates with a reasonable chance of winning were privately educated - only slightly below the 33% total in the current parliament.
By contrast, the figure for the population as a whole is just 7%.
Around half of the Tory candidates went to private schools, compared to 52% of the party's incumbents.
Some 19% of those standing for Labour were private pupils - almost double the existing rate of 10%.
More than half - 55% - of the hopefuls attended Russell Group universities, with a fifth Oxbridge educated. A quarter of current MPs went to Oxford or Cambridge.
Of the 260 candidates, 47 had careers as consultants, often in media relations, while 29 worked as barristers or solicitors and 19 as journalists.
The study included candidates selected by mid-December who were replacing serving MPs for the same party, or in target seats where they were assessed as having a reasonable possibility of winning.
Sir Peter Lampl, chairman of the Sutton Trust - a foundation which aims to improve social mobility - said: "This research shows that the next House of Commons is unlikely to reflect any more social diversity than the current crop of MPs.
"It underlines the importance of enabling bright young people from low and middle income backgrounds to get to the best schools and universities if they are to have a chance to play a part in making the decisions that affect all of our lives."