From 1922:
One pound of potatoes, 1 onion, celery, 3 pints water, 1 pint milk, 1 tablespoonful flour, 1 parsnip, 1 turnip, 1 teaspoonful sugar, 1 oz. butter.
Peel vegetables and cut up roughly. Make butter hot, and add vegetables. Stir until they steam; add sugar, salt, and water, and boil gently for one hour. Rub through sieve or colander, and return to saucepan ; add milk and allow to boil. Thicken with flour, and stir till boils. Season to taste.