David Verey has resigned suddenly as chairman of Lazard in London after 30 years, and has left the firm with immediate effect.
Verey, who joined Lazard in the stocks department in 1972, said: "I have loved my time at Lazard and it is now time for me to seek pastures new. I look forward to taking a break and to considering what I might do in the future."
Marcus Agius, vice-chairman, will take over from Verey as chairman. Agius has also been with the investment bank for nearly 30 years and has been involved in some of the most high-profile bids of the last two decades.
Agius said: "I am very much looking forward to taking over from David and continuing the success of Lazard in London and elsewhere."
Bill Loomis, Lazard chief executive, added: "David has been a marvellous colleague and leader of our London firm over many years."
Verey's surprise decision is likely to have been made for many reasons. Lazard has had a tumultuous few years which have seen the merger of the three houses - New York, Paris and London - into one united structure.
This move was cemented recently by the appointment of an American, Loomis, as chief executive of Lazard out of New York, by far the biggest part of the business. Verey is understood to be have been disappointed that he was not chosen.
At the same time Lazard was being stalked by the French corporate raider or greenmailer, Vincent Bollore, who forced the web of holding companies controlled by Lazard chairman, Michel David-Weill, to be restructured. Bollore walked away with handsome profits but Lazard did not enjoy the glare of publicity brought by either event.
Verey, who is understood to have earned 5m (€8m) last year in what was one of Lazard's best years, has not indicated whether he will continue in investment banking. But, after years of defending the role of the independent advisory bank, he will find it difficult to join one of the bulge-bracket houses. Verey has said on many occasions: "If you wanted to invent the perfect merchant bank you would create Lazard."