Berwin Leighton Paisner (BLP), Baker McKenzie and Pinsent Masons have been identified as the best performing law firms for social mobility, in a new ranking of UK employers.

The Social Mobility Employer Index, compiled by the Social Mobility Foundation, Social Mobility Commission and the City of London Corporation, ranks the UK employers that have taken the most action to improve social mobility in the workplace.

It is is believed to be the world's first ever social mobility employer index.

The list, which is topped by accounting firm Grant Thornton, includes 16 law firms, with BLP placing highest at eighth. Bakers was ranked 11th, with Pinsent Masons coming in at 15th.

BLP planning partner Tim Smith (pictured), who leads the firm's social inclusion group, said: "We pursue a number of initiatives; possibly the most significant one is in our graduate recruitment process. We use a contextual recruitment programme – we started using the tool after partnering with Rare Recruitment two years ago. What it give us is an ability to judge academic potential rather than just academic performance."

"We are also working up a proposal where we are calling on a group of other like-minded law firms – and there are many – and one of the leading social mobility charities to look at retention of socially disadvantaged employees. We will be looking at what HR and cultural practices can be changed to make people want to stay."

Three more firms make the top 20 – Burges Salmon (17) and Clifford Chance (19) and Linklaters (20) – while further down the list, Herbert Smith Freehills, Hogan Lovells and Simmons & Simmons rank 25th, 26th and 27th respectively.

The law firm contingent is completed by Eversheds Sutherland (29), Freeths (32), Brodies (39), Holman Fenwick Willan (43), DLA Piper (46), Charles Russell Speechlys (48) and Stephenson Harwood (50).

The index has been set up to encourage firms to share social mobility initiatives and progress to identify the sectors that are doing well in this field, as well as those that need to be more inclusive.

Firms were evaluated on criteria such as how well they work with young people, routes into work and recruitment and selection processes.