Scrub the clams well under running water. Shuck the clams, reserving the juices. Cut the larger clams in half. Mix the reserved juices with enough bottled clam juice to equal 3 cups.
Cook the bacon slowly in a soup pot over medium heat until lightly crisp, about 7 minutes.
Add the onion and cook, stirring occasionally, until the onion is translucent, 4 to 6 minutes. Add the flour and cook over low heat, stirring with a wooden spoon, for 2 to 3 minutes.
Whisk in the clam juice, bring to a simmer, and cook for 5 minutes, stirring occasionally. The liquid should be the consistency of heavy cream. If it is too thick, add more clam juice to adjust the consistency.
Add the potatoes and simmer until tender, about 20 minutes.
Meanwhile, place the clams and cream in a saucepan and simmer together until the clams are cooked, 5 to 8 minutes.
When the potatoes are tender, add the clams and cream to the soup base. Simmer for 5 minutes.
Stir in the sherry. Season to taste with salt, pepper, Tabasco and Worcesteshire sauce. Serve in heated bowls with the crackers on the side.