I want to know the answer to the following question:
What law required that a pub offer at least one beer from a brewery it wasn't tied to?
All the background I'm provided with is that "The landlord of a tied pub may be an employee of the brewery—in which case he/she would be a manager of a managed house, or a self-employed tenant who has entered into a lease agreement with a brewery, a condition of which is the legal obligation (trade tie) only to purchase that brewery's beer.". Is that enough to answer the question?
Answer: no