In a large saucepan over medium heat, cook the bacon, stirring often, until it starts to brown and has rendered some of its fat, about 3 minutes. Using a slotted spoon, transfer to paper towels to drain.
Cook the vegetables
Add the butter to the bacon drippings. When it melts, add the celery, onion, thyme, and bay leaf and sauté until the onion is translucent, about 2 minutes. Add the potatoes and stir well. Add the reserved clam liquor and 2cups (16fl oz/500ml) water and bring to a boil. Reduce the heat to low, cover, and simmer until the potatoes are tender, about 15 minutes.
Finish the soup
Add the milk and cream and stir to combine. Add the clam meat, heat through, and season to taste with salt and pepper. Remove and discard the bay leaf. Ladle the chowder into bowls, garnish with the bacon, and serve.