Before we enter the clouds on snow-capped Helvellyn, I glance back down at Ullswater. The early morning sun is bursting around the dark corners of High Dodd and Sleet Fell, sending a flush of light across the golden bracken and on to the hammered silver of the lake. The Guardian’s journalism is independent. We will earn a commission if you buy something through an affiliate link. Learn more. Further away to the south, ragged patches of snow cling to the high gullies. The nearest village, Glenridding, can barely be seen behind the leafless trees and all I can hear is the gurgle of the stream. It is the quintessential Lakeland scene: the steep slopes above the water, the soft colours and hard rock, all combining into something inimitable. And judging by the photographic and artistic record, it is one that has hardly changed since the Cumbrian wind first ruffled a Romantic poet’s curls. Our best loved national parks – the Lake District, Peak District, Eryri (Snowdonia) and Dartmoor – all officially opened 75 years ago, in 1951. It was the result of a long campaign, arguably begun by one of those Romantics, …