Restaurants Group chief executive Andrew Page has announced his intention to retire in August.
Having just predicted record profit for 2013 in a trading update earlier this month, with turnover up 9%, the decision by Page had not been part of the forecast.
Page will remain with the group as advisor to the chairman to facilitate an orderly handover. The Restaurant Group board will now commence the search for his replacement.
Chairman Alan Jackson said: "Both the Board and I personally would like to express our heartfelt thanks and congratulations to Andrew on the immense success he has achieved at TRG during his 12 year tenure. In that time the Company has come from having a market capitalisation of £75m to be valued now at over £1.2b.
"That would be some achievement even in a benign economy, let alone in the exceptionally challenging decade that we have endured."
Page added: "My time at TRG has been the most fulfilling of my 20-plus years in the hospitality industry. We took a business that had lost its way, re-structured and re-orientated it and then, from firm foundations, have grown it to become the successful company that we have today.
"Credit for this success belongs to the TRG team who have, at times, achieved the seemingly impossible and throughout have delivered a consistently fine performance for our shareholders. They are an outstanding group of people and it has been my privilege to lead them over the past 10n years."