Approach as for Sharp Edge (which looks spectacular under snow... and it is), following the Scales Tarn path from the A66, looping around the back of the mountain. Where the path splits close to the outflow stream from the tarn, keep right to contour around the foot of the ridge, before climbing into the little corrie bounding the north side of Sharp Edge. Foule Crag is the obvious broken face at the back of the corrie. approach time: 1 1/2 hrs max.
Several routes have been recorded on this face, and can be read about in the Cicerone guidebook Winter Climbs in the Lake District. The ground is fairly uniform with few defining features, allowing you to climb almost anywhere at about II/III. Hence following any of the recorded route descriptions on the steep face isn't all that easy. The rock is pretty loose and vegetated, so wait for a good freeze and expect most of your placements to be in snow or frozen turf.
The easy route described here skirts just right of the steeper face, following a diagonal left-right line, tracing the base of the steeper rock band above all the way: you can't get lost! At first go up easy angled ice flows, leading to more mixed ground. It is the most obvious line on the back wall of the corrie. Suitable for a solo. Since it comes into climbable condition fairly readily (by Lakes standards) it appears to be fairly popular, though it doesn't seem to have a name - unless some of the line corresponds to the recorded route Secondhand (II)...I'm not certain. On reaching easy ground turn left, following the cliff rim up onto the plateau above. The summit is about 700m to the south: selecting the right line of descent requires care in poor visibility. I'd recommend downclimbing Hallsfell Ridge, a lovely grade I arete. I'd probably steer clear of downclimbing Sharp Edge despite its modest grade (I or at most II) because of the slabby slatey nature of the rock underlying any snow.
Twin axes and 12-point crampons
If you're not soloing then you'll be relying on warthogs placed in frozen turf for protection, perhaps supplemented with a couple of ice screws and a deadman depending on conditions.
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