user: Question: When  David Ashburn Richard Westbrook is the gt3 winner and 1 is the round what is the length?
Columns: ['Round', 'Circuit', 'Date', 'Length', 'Pole Position', 'GT3 Winner', 'GT4 Winner']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Oulton Park', '25 April', '60 mins', 'No. 5 Scuderia Vittoria', 'No. 1 Trackspeed', 'No. 44 ABG Motorsport']
SQL:

assistant: SELECT "Length" FROM "Table" WHERE "Round" = 1.0 AND "GT3 Winner" = 'David Ashburn Richard Westbrook';