Mid `60`s we had Whirlwinds fitted with Bren guns,one mounted in the cabin door,one in the port side cabin window,co-pilot carried a Sterling SMG. If you wanted to be really `tooled-up` ,some aircraft could be fitted with 4 X SS11 missiles,wear `flak-jackets` and stick a 1/4 inch steel plate under your seat cushion,and my trusty Walther P38.
I think the Brens were .303`s(RAF issue-Army were .762 ) and the door gun firing position was lying on the floor...good for shooting at old oil drums in the S China Sea,or scaring crocodiles in the rivers.....