A study looking at U.K. employees found that those with working-class backgrounds, even if they get the right education and land a prestigious professional job, such as accountant or lawyer, still make about 17 percent less than those from middle- or upper-class backgrounds. 

"This class-origin pay gap translates to up to £7,350 ($11,000) lower annual earnings," said the study abstract. "This difference is partly explained by the upwardly mobile being employed in smaller firms and working outside London, but it remains substantial even net of a variety of important predictors of earnings."

The study's authors used their research to write a recently published book, The Class Ceiling: Why It Pays to Be Privileged. In it, they explain that people from more privileged backgrounds can excel over their working-class peers partly because they can afford to take more risks, as they can be reasonably confident that their parents will help support them through the difficult parts. Further, they said, parents with money can help their children move closer to where the best jobs are, and can support them through the primary entry-way into prestigious occupations: the unpaid internship. 

The authors also mention how sponsorships tend to reinforce these class boundaries, as people tend to like those that remind them of themselves. So, without even consciously thinking about it, someone from a middle or upper class background will have more in common with someone else from a middle or upper class background, and will be more likely to advocate on their behalf. The researchers noted that this same effect can be seen with regard to gender and race as well. 

In addition to the resources that people get from their background, the authors noted that workplaces are often governed by invisible codes of conduct that can be difficult for those with working class backgrounds to accurately parse. One example was that while certain companies have a very casual dress code, what's considered too casual can sometimes be difficult to determine for those not used to the environment. Furthermore, there are similar unspoken rules about affect, word choice and even how one sits. 

Overall, the researchers said that class is another dimension that should be considered when it comes to diversity and inclusion, especially given how it often it intersects with  factors like gender or race.