Another staple classic that has appeared in one form or another in most of the books that are considered classic today. The shot is from a fly that I tied some years ago for fishing on an old Partridge M 5/0 hook. I have to note that the GP underwing is easier to tie in if you select smaller feathers. The rachis changes shape towards the tip and becomes very hard to tie in if you use a large pair and strip the lower fibers off.
Here’s the pattern and notes from Kelson’s The Salmon Fly
Tag. Silver twist and yellow silk. Tail. Topping, Teal and powdered blue Macaw. Butt. Black herl. Body. In four equal divisions of Seal’s fur, light red-claret, light blue, dark red-claret and dark blue respectively. Ribs. Silver tinsel (preceded on large hooks by silver lace). Hackle. A natural black, from light red-claret Seal’s fur. Throat. A yellow hackle and Gallina. Wings. A tippet and breast feather of the Golden Pheasant (back to back) veiled with Teal, Golden Pheasant tail, Gallina, Bustard, and Peacock wing; strands of Parrot and Swan dyed yellow; and Mallard. Horns. Blue Macaw. Head. Black herl.
This old standard is used everywhere. For my own worl I always add a topping to the wing.