Early in my farming career, I was negotiating for Riverford to supply organic lettuces, cabbages and potatoes to a chain of supermarkets. The buyer asked me to visit their London offices the following Thursday.

When I asked if we could make it Friday instead, the phone went dead. I rang back, explaining that I had been cut off, only to be told: “Look, sonny; when we whistle, you jump. The only question is: how high?”