Leaving the top end of Longtown, you turn left to plummet down to cross the brook at the base of the Olchon Valley. Spanning the horizon ahead of you stands Black Darren, an impenetrable wall of rock forming a physical border between England and Wales. Following the rapid descent, you swing round a corner and immediately ramp back up; passing a farmhouse on your right, the slope hits close to 20% on the bend before easing. It’s not long before it is steep again up to the next buildings, round another right-hand bend, and the struggle continues. Creeping ever closer to the towering barrier ahead, you reach a final collection of buildings and a sustained stretch of tough gradient. By now you can see that the road doesn’t, thankfully, make it all the way to the top of the ridge, but bends abruptly right to climb for a few metres more before plateauing.