From Wikipedia: The 4 rear mounted .303’s could be fired forward, sorta. The turret was simply rotated into a forward firing position. Insulated cut off points in the turret’s rings prevented the guns from firing if they were aimed at the propeller blades or facing rearward at the plane’s tail. The guns function could be transferred to the pilot’s if/when desired but was not done often.
Interesting. Never knew about the forward rotation.