user: Question: Which Servedby has a Local authority [a ] of Thurrock, and a Station of Ockendon?
Columns: ['Station', 'Local authority [a ]', 'Servedby', 'Station users 2004–05', 'Station users 2005–06']
Types: ['text', 'text', 'text', 'real', 'real']
Sample row: ['Alresford', 'Tendring', 'Greater Anglia', 49400.0, 45100.0]
SQL:

assistant: SELECT "Servedby" FROM "Table" WHERE "Local authority [a ]" = 'Thurrock' AND "Station" = 'Ockendon';