For a thicker broth, substitute a cup of heavy cream for a cup of the milk.
Fry bacon in soup kettle until crisp. Remove with slotted spoon and set aside. Saute onion and celery in fat. Add potatoes, thyme, and clam stock. Simmer partially covered, 15 minutes or until potatoes are barely tender. Blend flour and milk and pour into kettle. Stir until blended. Add clams and heat thoroughly. Do not boil. Garnish with reserved bacon, crumbled.