WITH A SWEEP of his arm, Dave Murray shows where the proposed dam would straddle the valley. Starting at a distant hill in front of us, his pointing finger moves around to a ridge behind and above us.

The thing seems too gargantuan for this place – and too huge to fit in my head. I simply can’t see it. Before I can open my mouth to remark on this, Murray pre-empts me. ‘That’s quite a high wall,’ he says. As though in mitigation, he adds: ‘It’ll end up looking quite aesthetic when we’re finished.’