The chief executive of Tesco, the British multinational grocery and general merchandise retailer, could be forgiven for being less than delighted to see me. For the last few months I have been Philip Clarke's baiter-in-chief. It's not just that I have been shamelessly promoting a book about food security, which fingers supermarkets as one of the key culprits in a British farming crisis that has dangerously undermined our self-sufficiency. I have also clashed repeatedly with Clarke's spokespeople over Tesco initiatives to help people waste less food or eat more healthily.