The pool of open water that drains the mire reflects the deep blue of the sky and the patches of cloud that are bubbling up in the heat of the day. The surface is rippled in places where the warm breeze from the west sweeps across the low heathland, bringing the pungent, dusty scent of the summer New Forest. In the shelter of the gorse by the footbridge, electric blue damselflies cling to the tips of rushes, while occasional dragonflies – which I tentatively identify as emperors – cut abrupt, angular patterns over the water. Beyond the bridge, the path wanders upwards across the hillside, a bleached sand and flint trail bounded by stands of heather and tussock grasses. Over the 50 years I’ve walked here much has changed, but I’m pleased to see numbers of silver-studded blue butterflies still present. They are small, less than an inch across, but rimmed with white – making them easily visible as they tumble around the heather in the strengthening wind. Sadly, none of them settle close to the path, and to get a closer look would mean a risk to ground-nesting birds, so I watch their colourful antics from a distance. With the heat and humidity still rising, I climb the ridge to higher ground and the quiet shade of the trees. This ancient woodland of oak, birch and holly lies to the west of the broad valley mire, and I follow the path south towards the point where I can cross it again dry-shod. The route is complicated by the need to cross several side valleys, which seem oddly steeper and more numerous than when I was young. Pausing for a rest, I turn and catch a glimpse of a small sunlit clearing where a tree has fallen. Ferns grow in abundance, while saplings compete to reach the gap in the canopy, a dynamic system responding to a change of circumstances. I traverse a final deep valley and the trees change from broadleaved specimens to a mundane plantation of conifers. Sweating through the last mile in the hot resinous air, I wonder how long it will be before a thunderstorm restores some balance to the atmosphere. Much too long, as it turns out.