Candidates from a disadvantaged background aren't being awarded jobs at investment banks because they often wear brown shoes with a business suit, a report has suggested.

Firms recruit from a tiny pool of elite universities and hire those who "fit in", a study by the Social Mobility Commission found. They are "failing" to give jobs to talented but less advantaged candidates, partly because they flout the "opaque" City dress code.

Managers often select recruits who display "polish" and place as much importance on a person's speech, accent, dress and behaviour as their skills and qualifications, researchers said.