VERTICALLY CHALLENGED

I’m one kilometre above level ground, staring across a one-metre gap at a sheer slab of rain-soaked lava-rock. Beyond the toes of my boots, the rock drops away into a grinning crevasse. I can feel sweat trickling down my spine, despite the stiff mountain air. Why? Because I’m going to have to let my body fall forwards, into the void. I’m supposed to catch my fall with my palms on the slimy rockface in front of me, to create a ‘human bridge’, find some good handholds, then step one foot across the gap to climb onto the vertical block.

The thing is, it’s strictly a one-way move: get it wrong and there’s no way to reverse it – you’re going down. This is Tower Gap, on the Tower Ridge route up the north face of Ben Nevis, and my guide, Mike Pescod, has just sprung a surprise on me.

“I’ve seen people standing right where you are for about ten minutes, just trying to psyche themselves up to do this move,” he smiles across at me, nonchalantly holding onto the rope I'm tied to, looking like a PE teacher who's traded