user: Question: Who is the operator when Willowbrook was the bodybuilder?
Columns: ['Operator', 'Number purchased', 'Variant', 'Bodybuilder', 'Year(s) purchased']
Types: ['text', 'real', 'text', 'text', 'text']
Sample row: ['SHMD *', 1.0, 'G6HS', 'Northern Counties', '1952']
SQL:

assistant: SELECT "Operator" FROM "Table" WHERE "Bodybuilder" = 'Willowbrook';