Hammond Suddards Edge's London managing partner Gary Watson has resigned to join Ashurst Morris Crisp.
His move comes just five months after the merger between Hammond Suddards and Edge Ellison.
Hammonds management declined to comment on the move, but a Hammonds partner says: "Gary did have the ambition to be managing partner a while ago and that seems to have gone by the wayside. What he's said internally is that he wants to concentrate on being a lawyer."
Commenting on Watson's appointment, Ashursts property department head Simon Cookson says: "We have known Gary for many years. He is a well respected market operator."
It is understood that Ashursts has been searching for a property rainmaker for some time. Watson's arrival will shore up the firm's property department, which has undergone some upheaval in recent years.
Cookson says: "We have been thinking about the shape of the practice, which accounts for some of the comings and goings. These things happen. But we will continue to grow."
He adds that three property lawyers will be made up to partner level in the spring to boost the department further.
Although in recent years Watson has spent much of his time on management rather than fee-earning, he is still regarded as a big hitter in the legal property world.
He arrived at Hammond Suddards in 1994 from what was then Lovell White Durrant, and built a department which acts for the likes of Allied London Properties, Bastionen Group, the Mirror Group and Unilever Superannuation Fund.
He has a particularly strong reputation for City lettings work and has acted for a number of clients relocating to Canary Wharf. Ashursts acts for Canary Wharf on lettings, although Cookson denies that this is the connection that brought Watson to Ashursts.
Hammonds normally holds partners to a 12-month notice period but Cookson claims that Watson will join Ashursts "within six months".
One Hammonds source says: "It varies very much from partner to partner as to what deal they do."