Fourteen-partner London commercial firm Park Nelson has taken over the four-partner insurance practice Rayfields.
The bolt-on is part of the firm's on-going strategy to grow "in a controlled way," according to head of business development Richard Ireland.
Rayfields, which was set up by ex-Davies Arnold Cooper partner John Rayfield in 1992, specialises in professional indemnity insurance in the engineering and construction fields.
Rayfield, who is joining the firm as a consultant, said the move to a larger firm was driven by client need.
The firm's other three partners, David Herbert, David Reid and Frank Hallam, will join the partnership at Park Nelson. They are bringing with them all five of Rayfields' assistant solicitors.
John Kings, Park Nelson's head of litigation, said: "This will provide an extended depth and resource to our existing insurance and construction related practice."
Park Nelson, which specialises in commercial, litigation and insurance, now has 18 partners and 42 fee earners and boasts an annual turnover in the region of £5.5m in fees.