user: Question: How many directors worked on the episode with 2.27m (5) is the ratings?
Columns: ['Series No.', 'Episode No.', 'Title', 'Directed by', 'Written by', 'UK Ratings (BBC2 Rank)', 'Original air date']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [6.0, 1.0, '"London to Antwerp "', 'David Symonds', 'n/a', '1.96m (16)', '5June2011']
SQL:

assistant: SELECT COUNT("Directed by") FROM "Table" WHERE "UK Ratings (BBC2 Rank)" = '2.27m (5)';