People from higher socio-economic backgrounds were more than twice as likely to be found in senior roles compared with those from lower socio-economic backgrounds.
Measures of socio-economic background include parental qualifications, parental occupation, type of school attended and eligibility for free school meals.
Gender had less of an effect on employee progression in financial services, with men progressing just 2% faster than women.
Women from lower socio-economic backgrounds experience a double disadvantage, according to Nik Miller, CEO of the Bridge Group.
Women from more advantaged backgrounds progressed 21% faster than women from lower socio-economic backgrounds.
Men experience less of a gap, with those from higher socio-economic backgrounds progressing 13% faster.
Miller said: “The evidence is clear. Progression and hiring are heavily influenced by attributes available to those from higher socio-economic backgrounds.
“This includes drawing on family and alumni networks, and on cultural preferences that have been shaped over many years by this dominant group.
“Women typically experience the negative effects of being from a lower socio-economic background more significantly than men – who are more often able to use their working-class roots as an asset in the workplace.”
White men from higher socio-economic backgrounds are 30 times more likely to be found in senior positions compared with working-class women from ethnic minority backgrounds.
The research also found 20% of senior employees attended a private school – more than triple the national average of 6.4%.
Chris Woolard, social mobility partner sponsor at EY, told HR magazine that improving social mobility in financial services should be a priority for the industry.
He said: “Across the UK financial services sector, we can see that firms are striving to improve diversity, but there remains a long way to go.
“It is fundamental that the key challenges faced by people from lower socio-economic backgrounds – many of which are invisible – are better understood and more actively managed, and that there is a clearer pathway to senior levels.”
The report recommended that businesses should collect employee socio-economic data, publish it externally and set targets for socio-economic background diversity.
It also recommended developing targeted talent and leadership programmes that incorporate senior sponsorship.
Woolard added that leaders in financial services must start by tackling their unconscious bias against those from lower socioeconomic backgrounds.
He said: "Talent comes in all shapes and sizes, and banks, insurers and asset managers must all continue to work to remove unconscious bias, to recognise and celebrate diversity of background, and to create an aspirational workplace for all.”
The full report was the result of a survey of 149,111 employees of socioeconomic diversity campaign Progress Together’s membership organisations, which include some of the biggest financial companies in the UK, including in banking, insurance and asset management.