Joint head, Maurice Allen is understood to be quitting over his lack of autonomy from the US management and the firm's stilted attempt at European expansion.
Allene told the firm of his intention to quit on Friday but it is only today that the resignations of managing partner, Nick Holt and Martin Hughes, a founding partner of the London office came to light.
The firm's other joint head, Mike Francies will lead the London office singlehandedly following Allen's departure. He will also join the firm's management committee.
Holt and Hughes' resignations must have come as a shock to Francies: on Friday he told The Lawyer that he was not aware of any other lawyers wishing to follow Allen.
Allen first talked of his concerns with US management at a committee meeting over a week ago.
Last week US managing partner Stephen Dannhauser and senior partner Tom Roberts addressed an emergency meeting in London to try to appease fears of a management split.
But one insider says: "Morale is still at an all- time low."
Francies says: "I think that Maurice has reached a mutual understanding with the firm and decided to leave. At any firm people have issues, Maurice has issues and I have issues."