Alsop & Störmer's managing director James Allen said the move would free up the London practice to continue its international expansion. Störmer is expected to continue to focus his efforts largely on the German market.
Allen added that running two offices had become increasingly difficult. "Will wants an input in all of the projects that carry his name and this will give him more time to do that," he said.
Allen also sought to reassure clients that existing projects would not be affected: "It will be the same people working on the same projects, and clients won't notice any difference."
The two practices came together when Alsop needed a local partner for its work on the Hamburg ferry terminal. Störmer was unavailable for comment.