There are places in the Welsh hills where I’m assailed with a sense of unease. Often they are hill-passes. Below Garn Prys, the descent from Bwlch Blaen y Cwm alongside the Nant Llan-gwrach – “stream of the witch’s enclosure” – always brings an involuntary shiver; as does that from Bwlch y Ddwy Elor – “the pass of the two biers” – into Cwm Trwsgl, the “rough cwm”, and thence into Cwm Pennant. I walked this way recently in bright wintry weather and still felt a certain dread that only faded as I emerged from the cwm and started the rattly descent over slate spoil to the old tramway that contours round the western slopes of Moel Lefn and Moel Hebog. If anywhere in Wales is my milltir sgwâr, my own square mile, this is it. I lived here alone in a remote farmhouse through the most formative years of my life, walked these hills in all weathers, at all seasons. Bwlch y Ddwy Elor is one of the places I then mostly avoided. Was it just the quality of suggestion implicit in the name? Whatever it was, I’d hurry away. In Cwm Trwsgl, perhaps the physical form shapes the atmospherics? The huge, vegetated, falcon-haunted cliff that towers above the frozen llyn shadows the mountain hollow, acts as a sounding board for wind and rattle of stone. I’ve had doppelganger experiences here. Were they just amplifications of my own anxious heartbeat? Once, when hanging on a rope in the mist to clean a prospective new rock-climb on the fine, diamond-shaped slab above the pass into Beddgelert forest, all day I sensed voices drifting up from bronze age hut-circles below. Dusk thickened the mist. I coiled my ropes and hastened away. The name I gave to the climb, when completed, was the Exterminating Angel, from certain inescapably anxious moments experienced on it when faced with a fall on to boulders from the crux at 60ft. That feeling again hovered at my back this week as I gained the tramway’s sublime grassy belvedere, which contours round into Cwm Ystradllyn and a waiting car.