One of the oldest maxims in business is that scarcity sells. ("Buy now while stocks last!") It is just another expression of the law of supply and demand. So you have to hand it to those guys at the weekend farmers' markets that have become popular in the US, the UK and beyond. They may look like simple country folk trying to earn a few honest pennies from their back-breaking labour in the fields, but they need few lessons in how to separate urbanites from their money.

I know this because after a long and heroic resistance to the allure of the market just along the road from the Financial Times, I finally succumbed in the run-up to Christmas and decided to do some food shopping there. I had not intended to leave an hour or so later with 2kg of mini chipolata sausages, a mound of dry cured bacon and a vast ham - but how could I resist once told that the pigs from which the meat had come belonged to rare breeds? "Even rarer now!" I cackled gleefully as I staggered away with my booty.