Sydney,
I was informed while on Manly Beach, NSW, that the galah is a bird - a beachcomber was on promenade with a pet galah on his shoulder - so incredibly stupid it would walk and stand in the middle of a road, with traffic, or some such anecdote.
So, a "flamin' galah", other than a jibe meaning "you dolt/dumb-dumb, etc." could be an idiot bird alight and burning bright.
Fletched Floydian,
Byron