This is a classic Catskill dry fly tied by Niklas Dahlin.
Hook: Partridge SLD
Wing: Wood duck split wing
Tail: Badger
Body: Yellow floss
Rib: Gold tinsel flat
Hackle: Badger
Charles Cotton says in “the notes of Theodore Gordon”. “Golden brown spinner, is like a small mayfly. Summer duck wing, badger hackle and a golden body, Mr Gordon says his friends find it kills so well they call it the Gordon.”