A British Zero becomes a heavier radar-directed fleet fighter

What changes if the Royal Navy operates the A6M Zero in 1939?

It gains a capable long-range radar-directed fighter, although British production would likely make the aircraft heavier and more powerful.

The Zero would give the 1939 Royal Navy a long-range fighter able to escort strikes and use climb-and-dive tactics. Carrier radar direction would help place it against incoming aircraft more effectively than purely visual patrols. A British-built version would not remain identical to the Japanese machine. A more powerful engine and a heavier structure would trade some of the original's extreme lightness for British operating requirements and survivability preferences.