In a hotel function room in Dublin Airport, Christine Tacon ends a recent whistle-stop tour of Irish authorities and business bodies with a presentation to farmer representatives. The UK’s first Groceries Code Adjudicator has a business-like and efficient manner about her, yet she is also available and engaging. Tacon is clearly proud of the changes she has brought about in commercial relations between British retailers and their suppliers, and her style has a lot to do with it. Although she has the authority to enforce hundreds of millions in fines on supermarket chains, she has not yet used it. She…