In heavy kettle cook bacon over a medium heat until fat is released. Add onion and saute until soft. Add carrots and celery and stir to coat. Add bay leaf, red pepper flakes and tarragon. Cook vegetables and seasonings until tender. Add tomatoes and clam juice. Bring to a simmer. Add potatoes and simmer until tender, about 20 minutes. Add parsley and clams. Simmer for 10 minutes more and serve.