user: Question: Name the total number directed by for uk viewers being 6.86
Columns: ['Story No.', 'Episode', 'Title', 'Directed by', 'Written by', 'UK viewers (million)', 'AI (%)', 'Original air date', 'Production code']
Types: ['text', 'real', 'text', 'text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['157', 1.0, '" Rose "', 'Keith Boak', 'Russell T Davies', '10.81', 81.0, '26March2005', '1.1']
SQL:

assistant: SELECT COUNT("Directed by") FROM "Table" WHERE "UK viewers (million)" = '6.86';