Julian Sargeson, chief executive at the Laurel Pub Company, has abruptly quit his role at the fast growing operator.
A company spokesman said no date had been set, but Sargeson would be leaving shortly and his responsibilities would pass to executive chairman Ian Payne until a successor could be found.
Laurel controls the Hog's Head, Yates and Slug and Lettuce brands. Originally created after the sale of 3,000 Whitbread pubs in 2001, the company was snapped up by property magnate Robert Tchenguiz in late 2004.
Successful bids for Yates Group and the majority of defunct bar operator SFI followed, giving it more than 400 high-street pubs.
The company recently reorganised its operations into three divisions: Circuit, Quality Food and Town Local.
In an unconnected development two Laurel directors are also moving on from the company.
Nigel Stock, head of finance, is moving to National Car Parks to become group financial controller. Caroline Craik, purchasing director, is off to Ultimate Leisure as commercial director.
By Chris Druce