Launching next month, the GAPbuster programme provides a benchmark report for Londis retailers to pit their performance against each other and the multiples.
Some 50 Londis stores have subscribed, but the company wants more to get involved.
Ramesh Shingadia, who owns a Londis store in West Sussex and trialled the programme in June, said: “It was a useful exercise - through GAPbuster you can learn exactly how an outsider sees your store. The feedback was really valuable.”
Under the scheme, retailers can expect a monthly visit from a mystery shopper who will judge availability, cleanliness, appearance, and customer service. Each visit, followed by a report pointing out areas of improvement, costs £43.
Ross Halliday, head of marketing at Londis, said: “It is designed to deliver improvement in customer service, which is achieved by continuous reinforcement of best practice and focusing on action plans.”