Clothes may make the man, but it’s specifically the shoes that’ll make an investment banker.

That’s one of the key takeaways from a recently published report by the U.K. Social Mobility Commission that found poorer job applicants may be discarded at a banking interview for simply wearing the wrong color of shoes.

The researchers found that some senior executives deem it unacceptable for men to wear brown shoes with a business suit as it doesn’t fit with the classic perception of a polished city banker.

“It is shocking,” said Alan Milburn, chair of the Social Mobility Commission, “that some investment bank managers still judge candidates on whether they wear brown shoes with a suit, rather on than their skills and potential.”

Some senior managers still have an old-school perception of how to dress as a banker Getty Images

That mostly happens to less affluent candidates because their upbringing and background means they aren’t aware of the “opaque” city dress codes, according to the report. Managers instead often picks applicants who fit the traditional image of a banker, including how the candidate speaks, behaves and dresses.

“Bright working-class kids are being systematically locked out of top jobs in investment banking because they may not attend a small handful of elite universities or understand arcane culture rules,” Milburn added.

“While there are some banks that are doing excellent work in reducing these barriers, there are still too many that need to wake up,” he added.

The banks may not have woken in their recruitment process, but internally things are happening on the clothing front. J.P. Morgan Chase & Co. JPM, -3.09% and Goldman Sachs Group Inc. GS, -0.44% are among biggest banks loosening their collars, by adopting more relaxing dress codes.

In a break from tradition, J.P. Morgan just allowed employees to go casual on most occasions, while some units at Goldman in London experimented with “casual summer”, which ended with the arrival of September.