Richoux Group managing director Edward Standring has resigned from the business with immediate effect.
Standring had been managing director of the company, which operates the Richoux café brand as well as Dean's Diner, Villagio, and Zippers, since 2011.
There are five Richoux sites in central London, while Italian restaurant brand Villagio has eight restaurants in London and the South East. There are nine Dean's Diner sites, modelled on 1950s US diners, while there is just one Zippers, in Chatham in Kent.
The business is owned by shareholders including Philip Kaye, Salvatore Diliberto, Robert A Rayne, and Michinoko Ltd.
In a brief statement to the City this morning, Richoux Group said it would "like to thank Mr Standring for his work with the company and wish him all the best for the future".
It has not yet announced the appointment of a successor to Standring.