Place the potato, celery, onion, garlic, basil and chicken broth in a pot. Add salt and pepper.
Cover the pot and bring to a boil. Reduce heat to medium and cook until vegetables are tender. Remove from heat and let cool slightly.
Then blend the potato mixture until the mixture is smooth. Return to the pot and add milk, butter and Worcestershire sauce. Give it all one more stir and cook for about 4-5 minutes over medium heat (don't let boil). If the soup is very thick, add more milk. Taste and adjust seasonings.
Garnish with fresh basil. You can serve the potato and celery soup with fresh lemon juice on the side.