Hackle and wing Natural grey hackle (Troutline Ultra Selected CDC)
How to tie it
Start the white 70 denier at the eye and run it back to the bend. White keeps the picric-dyed pheasant honest. Those golden-olive shades are the whole reason for the fly and a dark thread underneath kills them.
Tie in a sparse tail of Coq de Leon, a shank and a bit long, so the back of the fly is held up on stiff fibres.
Tie in three or four picric-dyed pheasant tail barbs by their tips and wrap them forward in touching turns to the 65% mark. Those picric shades are what grayling and trout key on in autumn.
Tie in a natural grey CDC feather at the 70% mark and take two turns as a hackle, but deliberately leave some barbs loose and pointing outward rather than combing everything into a neat collar.
Take those loose barbs and tie them in as legs, splayed to the sides and slightly down. This is the detail that balances the fly: the legs spread the load on the surface and give a far better water print than a tight hackle.
Stand the remaining CDC up as a short wing, whip finish a small head, and trim nothing you don't have to. The scruffiness is doing work.