Having spent a lot of the summer away from home, things have moved on without me, and the impossibility of being everywhere to see everything weighs heavy – a familiar, low-key fear of missing out. I decide to devote an entire morning to walking, regardless of gusty winds and persistent rain. If I used a tracking app, my route would seem a strange one: I zigzag, stop and start, stride out, then dawdle. But an aimless wander gradually becomes a tour of old friends. I offer a few words to the grandest oak on the Castle Howard estate (though not the oldest), then pause at a trackless spot in the wood where once, in a bout of post-Brexit despair, I encountered a horned forest god who reminded me that I still belonged. He lives there still, but invisibly now. I roam all over a pasture with an old pond that I imagine might once have refreshed the heavy horses or ox teams that used to plough the level ground either side. You can still follow the rigg and furrow corrugations left by the communal effort to cultivate and care for this land long before enclosure. The castle and the folly overlooking this field were dreamed up by John Vanbrugh in the early 1700s, but are now perhaps best known from screen adaptations of Brideshead Revisited and Bridgerton. From the castle, the folly is framed by trees, but from this spot, it looms incongruously above the cowpats. Its dominance is tempered by its romantic title, “Temple of the Four Winds”, and by the lichens and grime that smudge its stonework. Next to the temple is another veteran tree. Not an oak this time, but a birch. We don’t think of birches as ancients or giants. But with its gnarled trunk and huge boughs, this one is stronger and more burdened than it gets credit for. It has grown in strange ways at the command of parasitic fungi and is now weighed down by witches’ broom galls. The growths look loose and twiggy, but each weighs tens of kilograms. I lean into the trunk as a squall strikes, and the canopy begins shedding diamond drops of water and the first golden leaves of autumn, and I realise how tired we both are. Country diary is on Twitter at @gdncountrydiary Earlier this month, Amy-Jane Beer won the Wainwright prize for nature writing, for her book, The Flow, which is available at the Guardian bookshop. Fellow diarists Elizabeth Jane-Burnett and Amanda Thomson were also nominated for the award