Professionals with working-class backgrounds make, on average, 6,800 pounds, or about $8,400, less a year than their colleagues from more privileged families.

The study attributed some of that difference to education and other factors, but it also found that those from working-class families who have exactly the same occupational role, education and experience as their colleagues from more advantaged backgrounds are still paid, on average, 2,242 pounds, or about $2,800, less a year. The study found the gap was especially wide in the financial and medical professions.

The class pay gap is worse for women and people from minority-ethnic backgrounds, according to the research, which was carried out for the commission by the London School of Economics and University College London. The study looked at data from nearly 65,000 people drawn from the U.K. Labor Force Survey.

One reason for the pay disparity, the study suggested, is that children of professional families are more likely to work for larger companies and in London, where salaries are higher. Another is what it called “cultural matching,” whereby those making the hiring decisions extend job offers to those with whom they feel comfortable based on social and cultural traits.

That, of course, is another form of what the study calls “outright discrimination or snobbery.”

Tim Farron, the leader of the Liberal Democrat party, said the report “exposes the gaping class divide at the heart of our society that we all already knew existed.”