"Wasn't the Darby hackle the thing that made it the bomb?"
I knew Harry & Elsie Darbee and used to stop in there house/shop and I'd watch them tie. They had their fly tying desks side by side and they had all sorts of bamboo rods in cases inthe corner of the room.
In regard to the dry fly hackle that Harry used; he was raising his own roosters and I believe he got his genetic chicks from a gentleman named Andy Miner. They were nice dun feathers but by no means anywhere as consistently long and stiff as later capes, and saddles, of Metz, Hoffman, and later Whiting came out with after serious scientific genetic breeding in the early 1980's.
I don't believe that the Darby hackle had anything to do with the popularity, or effectiveness, of the Dark Hendrickson. The fly had already been around for decades.
I bought a flamed Leonard Baby Catskill 7' #4 from Harry for $200.00.
A few times when I went to the Darby house there was someone there of reknown in the fly fishing world of the early 1960's. I met Sparse Grey Hackle (Alfred Miller) Larry Solomon, and others. Everett Garrison was still alive, and making rods, but the waiting list was so long that it was pretty much impossible to get one. I did though get a Thomas 8' 6" 3 piece, the Leonard, a couple of Orvis rods, a Walt Carpenter 7' 6" #5 that I still own and a Miney Hull rod which I sold long ago.
In all the time I visited the Darbees which was about ten years I never saw either one of them ever fish the Willowemoc or Beaverkill. I don't think Harry had fished the local waters in twenty years. He said he still did some Atlantic salmon fishing on the Margaree but I think he had lost all interest in fishing the local waters.