Allen & Overy's managing partner of litigation, Andrew Clark, is quitting his job as London department head to focus on finding the firm a new home.
Litigation partner Peter Watson will take Clark's place when he stands down in the autumn.
Clark has been appointed to oversee the firm's move, when its lease of One New Change, owned by Land Securities, expires in September 2006.
He will be co-ordinating the project with fellow litigator and senior partner John Rink.
The appointment will follow the retirement of business services director Rodney Barker this week. Barker chaired the subcommittee responsible for the move.
But it is understood that Clark will not be directly replacing Barker on the committee, as the project moves closer to signing a deal. Clark said: "It's more of a client role than a lawyer role."
The firm is mooting the idea of shifting the entire firm to Canary Wharf.
Barker said Allen & Overy would set up a Canary Wharf office, but ruled out a split strategy, despite plans to establish a satellite office in client Citigroup's office. "We are not splitting up the firm," he said.
Clifford Chance was the first major City firm to announce plans to quit the City, when its lease expires in 2003.
A Docklands solution would also suit A&O, which is looking for a bigger site. Barker said that a decision had not been taken on the five options on the table.