The ‘Quicknic Code’ is a new scientific formula developed by the bakery chain that determines which regions of Britain receive a lunch deal based on weather conditions and customer behaviour. How does the Greggs 'Quicknic' code work? Zoe Harris, customer and marketing director at Greggs, said: "Nobody has ever put mathematicians, scientists and Sausage Roll makers together to create a lunch deal before, but that’s exactly what we’ve done. "Determining who gets the Quicknic deal isn’t based on just one weather forecast. Greggs is advising customers to check their local shop or its social media channels to see when the Quicknic deal is available in their area.