Keith Waterhouse is very particular about what lunch is not: 'It is not prawn cocktail, steak and Black Forest gateau with your bank manger. It is not civic, commemorative, annual office or funeral. It is not when either party is on a diet, on the wagon or in a hurry.' He is equally precise about what lunch is: 'It is a mid-day meal taken at leisure by, ideally, two people. Three's a crowd, four always split like a double amoeba into two pairs, six is a meeting, eight is a conference... A little light business may be touched upon but the occasion is firmly social. Whether they know it or not, for as long as they linger in the restaurant they are having an affair. The affair is lunch.' The Theory and Practice of Lunch is an authoritative and delightfully witty manual on the art of taking the most agreeable meal of the day, written by a shrewd observer of the passing show who listed his sole hobby in Who's Who as 'Lunch'.