The Sheffield-based firm, which has 15 offices across Great Britain including one in Glasgow, has been working with investment bankers at Rothschild and is aiming for a £500 million valuation, according to Sky News.

If successful, it will easily outstrip law firms like DWF (£282 million), Knights Group (£359m) and Keystone Law (£195m).

A spokesperson for Irwin Mitchell said: “We’ve taken no decision to introduce external investment. We remain in a strong position financially with our existing bank facilities offering us sufficient firepower to invest further in the growth and transformation of our business.”