The dressing that I have is from Flyfishing Skills on Stillwaters (Peter Mackenzie-Philps):
SHREDGE
A slight modification of Tony Knight's pattern
Hook Yorkshire Sedge Hook size 10
Thread Olive
Body Dubbed seal's fur or substitute, in a light cinnamon colour (tobacco). Aim for a thicker front end, or a fat carrot shape.
Wings Any pale grey feather, laid well back. Best of all to tie one wing in at a time, on the sides, not on top.
Hackle Bearded, a pale ginger colour, known nowadays as Carnill Ginger. hen hackle is best, but cock will do.
The fly can be weighted, and fishes best in the summer months, and after midday. I have had most success fishing this pattern very slowly, in a sink and draw.