KPMG features second on the list of the top 50 employers, with Deloitte at 5 and PwC at 7. EY is the only one out of the Big Four that does not feature in the top 10, coming in at 16.

HMRC and Treasury both appear on the list at 37 and 40 respectively.

The Index is a joint initiative between the Social Mobility Foundation and the Social Mobility Commission, in partnership with the City of London Corporation. Nearly 100 employers from 17 sectors, who collectively employ just under one million people, submitted entries about their practices and procedures in areas including working with young people, recruitment and progression.

The aim of the Index is to encourage firms to share their initiatives and progress in becoming more inclusive employers and to reveal which sectors and companies are taking the issue of social mobility most seriously.

Firms are now increasingly asking employees about their social background. Four in ten ask the type of school attended (41%); a quarter ask if an employee received free school meals (26%); 39 % ask if employees were the first in their family to go to university; around one in ten ask about parental occupation (7%) and the postcode where an employee grew up (11%).

Almost one fifth (17%) of the firms now set social mobility targets as part of their business strategy with the firms collectively scoring the highest on their work with young people, providing outreach activities for over 663,000 young people, nearly 10,000 work experience placements and over 5,000 mentors. However, they score lowest on helping people from lower-socio economic backgrounds to progress in the workplace.

David Johnston, chief executive of the Social Mobility Foundation, said: ‘All the Top 50 firms in the Social Mobility Employer Index should be applauded for the progress they are making towards ensuring that everyone has the opportunity to get in and get on – regardless of their background.

‘While no one firm has cracked the issue and there is still progress to be made, they should be congratulated both for having prioritised social mobility and for being prepared to have their processes and practices independently scrutinised.’

The Rt Hon Alan Milburn, chair of the Social Mobility Commission, added: ‘Improving the UK’s dismal social mobility record requires new action by employers and not just governments. It is very welcome that more employers are changing their workforce strategies to ensure they don’t lose out on talented people from less privileged backgrounds. The top 50 are paving the way and I thank them for their efforts. Where they are leading, I hope others will follow.

‘The annual publication of this Index aims to shine a light on how and where progress is being made. Employers that have employees at all levels from a rich variety of social backgrounds are better placed to meet the demands and uncertainties of today’s world. Social mobility is good for employers. And employers can make a major contribution to creating a more mobile society.’

The top 50 companies are available here.