The chair of Wagamama owner The Restaurant Group has said he will step down for personal reasons following a growing chorus of calls from activist investors for him to go.

TRG, which also owns Italian-American chain Frankie & Benny’s and the Brunning & Price pub chain, said on Friday that Ken Hanna, its chair since January last year, would not seek re-election at the group’s annual general meeting next year and the group would initiate a search for his successor.

Hanna’s decision to leave was “due to personal reasons”, according to TRG. But his exit will be interpreted as a major concession to activist investors that have called for his removal as part of a campaign for a shake-up and partial sale of the casual dining operator.