Henry King, Denton Hall's chair, has stepped down after his three-year term in office following an increased workload outside the firm as chair of three companies.
King is chair of Rentokil, which has just successfully acquired BET, and was recently appointed chair of City Centre Restaurants. He is also the chair of GKR, an executive search company.
The firm said that the timing of the announcement - The Lawyer revealed last week that Dentons had dropped out of merger talks with Cameron Markby Hewitt and McKenna & Co - was not significant.
King, a specialist in international tax, mergers and acquisitions, and joint ventures, said that the move would give him the time to continue to work for the firm advising several major clients.
When King won a contested election for chair in November 1993, he was the first to be elected under a new system which allowed all equity partners to vote on senior departmental candidates.
His post will be taken by 41-year-old James Dallas, a partner in the energy and natural resources group who played a key role in the recent development of its burgeoning PFI work. Elected unopposed, he has been a member of the partnership board for six years.
Dallas said he was taking over just as Dentons' strategy, developed three years ago to concentrate on utilities, media, telecommunications and major projects work, was "really paying off".