CAC Wirraway
Considering it first flew in1937 and the last retired in 1959, speaks for itself.  Me thinks the Pratt & Whitney R-1340 had a lot to do with it. 
Plus a likely simple and robust construction.The dual Lewis guns add a “cool” touch.  If I were a gunner, back there, I’d give the “T” hand symbol, for a “time out,” to the enemy pilots, while I changed magazines…