Melt the butter or margarine over medium heat in a large saucepan or stockpot; add the onion, garlic, carrot, bay leaf, and thyme. Cook, stirring occasionally, until the onion softens. Add the lobster shells, and cook until they turn red.

Add the wine and tomatoes. Bring to a gentle boil, and simmer for about 5 minutes. Add the stock and bring to a boil. Reduce the heat to medium, and simmer for 20 minutes.

Remove the bay leaf. Remove the lobster shells; remove the meat from the shell, and set aside.

Place the soup, in batches if necessary, in a blender or food processor; process until smooth. Return the soup to the pot, and bring to a boil. Add the cream and any lobster meat you may have, and heat through. Check for seasoning. Sprinkle with the parsley, and season with salt and pepper. Serve.