Accountancy firm Grant Thornton has topped a national list of employers taking the most action to improve social mobility in the workplace.

The company, which has an office in Norwich, was ranked highest in which is believed to be the world's first social mobility employer index, compiled by the Social Mobility Foundation and the Social Mobility Commission in partnership with the City of London Corporation.

It beat off other professional services firms KPMG and PricewaterhouseCoopers, supermarket Morrisons and banking firms JP Morgan and Standard Life to secure the top spot.

The index ranks British employers on the actions they are taking to ensure they are open to accessing and progressing talent from all backgrounds.

Among the top 50 firms were car rental company Enterprise, EDF Energy, O2, Rolls Royce and the BBC.

Several big banks including Barclays and Lloyds made the index, while the Department for Education, HMRC and the Ministries of Defence and Justice are also listed.