dd310, your post and indeed this thread is a classic example of the power of pprune. I am now the wiser thanks to you (and as ever to Google!). The aviation crown you mention is not the Adastral but the Astral Crown (Google politely asking if I meant the latter, of course I did!).
Not only is there a Naval Crown and an Astral Crown, the Army has its own too, the Camp Crown!
You boy, did I hear tittering?
https://en.wikipedia.org/wiki/Astral_crown