One of Weil Gotshal & Manges highest fee earners, New York litigator Dennis Block, is leaving the firm over disagreements about strategy, including the expense of the London office.
It is understood that Block, who is said to have personally taken $2m in profits last year (the firm's average per-partner profits last year are estimated at $735,000), was one of only three or four partners in the firm who voted against the creation of a London office staffed by English lawyers two years ago.
He sat on the firm's 12-strong management committee and, in recent years, had had several bitter disputes over strategy with 71-year-old Ira Millstein and Harvey Miller - the firm's two most senior lawyers and de facto heads.
Block, 55, was next in seniority and would have taken over as de facto head of the firm following Millstein's and Miller's retirement.
It is understood that Block was opposed to diluting profits by investing in international offices and UK lawyers and also wanted Millstein to stand down as head. The London office now has 60 lawyers and 40 more work in offices in Brussels, Budapest, Prague and Warsaw.
Matters were brought to a head when he questioned Ernst & Young on the positive results of a consultation it had undertaken for the firm on its international practice.
The management committee confronted Block over this and both sides mutually agreed that Block's "irreconcilable differences" meant he would have to leave.
Maurice Allen, Weil Gotshal's London managing partner, stressed that although Block had opposed international investment: "We never felt that that hampered the development of the firm's international practice. In practice his views didn't hold sway within the firm."
He said for the whole firm the fact that the "senior partners weren't gelling" led to "unresolved issues for a number of years". He added that Block's departure had led to "a certain amount of relief".
Block, whose clients includes Merrill Lynch and General Electric, has not yet decided where he will go. It is thought one lawyer from the business and securities litigation department that he headed may go with him but five others have pledged to remain.