Thompsons has merged with rival Rowley Ashworth, making the largest trade union firm in the UK.
Thompsons head of policy and public affairs Tom Jones said it was a “coming together” of two like-minded firms.
“The logic to this is that our clients overlap,” he said. “They were the other major trade union law firm.”
Thompsons counts Unison, Unite and the GMB as clients, as did Rowley. The unions refer personal injury (PI) work to the firm from their members.
Both firms have offices in the same location, which will be consolidated into a single site.
The combined firm, which will be known as Thompsons, will employ more than 1,000 people and have 26 offices across the UK, including recent openings in Dagenham and an associated office in Aberdeen.
Jones said all Rowley equity partners will transfer to Thompsons and Rowley managing partner Keith Roberts will assume an equity partner position, although it remains unclear whether he will take a management role.
“We have a corporate structure and they’ll slot into that,” Jones said.
The merger comes a year after Thompsons united with Manchester PI outfit Whittles, taking on 65 staff. Whittles managing partner Chris Strogen joined Thompsons’ equity.
According to one source, the trade union legal sector is a “depleting market” with Thompsons sweeping up several rival firms.
“Russell Jones & Walker is the only real competition to Thompsons,” the source added. Jones, however, denied that the firm was on an acquisition trail.