At this time of year, with few leaves on the trees and little in the way of surface hatches, Grayling are likely to have their heads down concentrating their efforts on food sources on or near the bottom of the river. During the Trout season the fly angler will rightly concentrate much of his effort upon visual lies of the river such as eddies, pools and overhanging branches. The Winter Grayling angler needs to broaden their minds and think of the river in three dimensions and not two.
Those fast, deep stretches of river that look unfishable will have small depressions on the riverbed or a rock or two in which a Grayling can lie behind – remember that the current will be slower towards the bottom of the river than on the surface. In order to be succesfull with the winter Grayling it is imperrative that the angler is able to get his fly deep. Beaded flies are good but in faster deep water they will only get down maybe a foot or two before you reach the end of your drift. In these situations you will need to add some lead shot to the leader or a dropper with a heavy leadhead or cased caddis pattern.
In my opinion getting deep is far more important that fly pattern. Most traditional style nymph patterns such as hares ears and pheasant tails will work provided they are fished at the correct depth.
In order to know you are fishing deep you must feel the nymph bouncing along the bottom, getting snagged on rocks and boulders is par for the course in this type of fishing. If you are not feeling bottom – you are not fishing deep enough!