In a large stainless-steel pot, render bacon over moderately high heat. When cooked but not crisp, add the flour and stir to form a roux. Allow the mixture to cook while stirring constantly until you can’t smell the raw flour, but do not let it brown.
Add the onions, celery, leeks and continue stirring. Reduce the heat, and cover the pot to extract the water from the vegetables, about 3 minutes. Then remove the top and stir the vegetables to avoid any browning, and to let the liquid cook off. Then add in clams, shrimp, lobster, and clam juice. Continue stirring and bring the liquid to a simmer.
Add cream, bay leaf, thyme and potatoes. Simmer for 45 minutes, until soup has developed a thick consistency. Season with Tabasco and Worcestershire sauces, and sprinkle with chopped parsley.