Saute celery & onions in 2T of butter for 10 minutes until opaque. Add to chicken stock. Add the juice only from the clams reserving the meat. Bring to a heavy simmer and add pepper and thyme. Add the potatoes skin on and simmer until cooked but still firm. While the potatoes are cooking in the soup, warm the milk. Make a roux with the butter & flour and when cooked, add to the milk off heat. Stir and return to the heat and stir until thickened. Set aside. When the potatoes are just tender, add the clam meat, cook for 2 minutes then add the milk sauce. Simmer for 8 minutes then add the sherry. Simmer for 2 minutes more, garnish w/ parsley and serve. From the collection of Chuck Rippel