Soak the bacon joint for four hours. Put into a saucepan with fresh cold water, bay leaf, peppercorns and sugar. Bring to the boil, then reduce heat and simmer for two hours. Drain bacon and strip off skin. Sprinkle fat surface of bacon with a little oatmeal or browned breadcrumbs.
To make the sauce, melt the butter and stir in the flour gradually, away from the heat, until the mixture is smooth. Add milk and stock gradually, beating well, and stir over low heat until boiling. Simmer gently, stirring often, and add parsley, salt and pepper to taste.