Lay a base of tan thread from behind the eye to the start of the bend.
Spin an Antron dubbing noodle onto the thread, thin at the front and thicker toward the back. Push the noodle up close to the hook, take two or three wraps to get purchase, then pull and spin it tighter. Dub the body forward to just past the halfway point.
Catch in two strands of peacock herl at the front of the body and take four or five turns forward, twisting the strands together if they start to spread. This gives the two-tone body. Tie off. You can put tension on the thread and simply break the herl off to save the rest, but then take a couple of extra wraps to be sure the ends are caught.
Tie in a partridge after-shaft feather in front of the herl. The feather is delicate, so wrap it with your fingers rather than hackle pliers: two or three turns, pushing it round and holding it with a finger as you go. Two turns is enough.
Trim the tip of the after-shaft and take a few extra wraps to smooth the base for the hackle.
Take a partridge shoulder feather, grip the tip and pull an even number of barbs back on each side to make a tie-in point. Catch it in on the near side with two or three firm wraps, then a couple of wraps to smooth the step. Do not fold the stem back over itself if you are already close to the eye.
Grip the tip with hackle pliers and take two complete turns of partridge hackle. Two is enough. Catch it off with a couple of wraps and trim the stem before releasing the pliers.
Sweep the hackle back and ramp the thread up to build a good-sized wet fly head, leaving room for the whip finish and cement.
Leave the thread at the back of the head before you whip finish so no wraps slip forward and crowd the eye, and take care not to trap any hackle fibres. Pull tight, slice the thread off, and add a drop of head cement.