Beautiful fly, Scott
A bit of a follow-up from Martin's comment on the partridge front hackle. I use another french wet fly pattern, the Assassine, that is close to the D22 above. It omits the tail, the yellow body is Pearsall's, and the dun hackle is a full palmer, front to back (then ribbed with the Pearsall's). The front hackle is also Partridge - it is a great fish catcher and also a great looking fly.
Alberto