My personal favourite has to be "Biggles Flies East".
Spys, dodgy arab tribesmen, sabotage, more spies, evil german ace gets his come-uppance, shullduggery, assassins, an inept german general and, strangely enough (considering other threads currently being flogged out...) Biggles finds himself with a german squadron and indeed recommended for the iron cross after dragging his wounded german gunner across the desert in a pantechnicon fashioned from thier downed plane.
A good yarn all round.
I think probably W.E.J best...I have
every biggles story now so I feel qualified to comment.
Chris