Eighteenth-Century Pea Soup

• 7½ cups (1.8 litres) old green peas (6 lb/3

Bring about 3 quarts (2¾ litres) of water to the boil in a very large saucepan. Add the old peas, celery, half the lettuce, and the mint. Cover the pan and boil gently for about 20 minutes or until the pea