The planned long sultry walk at Oldbury failed to materialise on Sunday – like a mirage it shimmered but gradually receded from view as the unaccustomed warmth altered rhythms and weakened resolve. A midday family cycle from Tonbridge to Penshurst Place along the River Medway formed Saturday’s low weald excursion, coupled with a wander around the Tudor mansion’s sumptuous gardens. It was a gloriously warm day but not as energy-sapping as what was to come. On Sunday morning I did a bit of gardening at home in SE London – Penshurst’s vivid borders had inspired me to cut back some of the long grass and weeds to show off what flowers were growing in our sun-bleached south-facing front garden. But as the temperature roared past 30C by 11am it all felt like too much hard work; by noon I withdrew to a book and a cold drink, reflecting on how physical gardening actually is. I also pondered how sad it was that the once common municipal open air pool has largely disappeared from London apart from busy lidos at Tooting, Charlton and Brockwell Park. Nearby, the River Pool near Bellingham Play Park had become a paddling pool – I just hope its clean enough for that.

At Penshurst Place I saw more house martins than I’d seen anywhere this year; I’d seen some in the distance at Chartwell from the Westerham/Hosey walk a few weeks previously and a few on the Thames west of London. Among their merry throng, swallows and swifts also proliferated. Finches – green and gold – called and flitted from fruit trees and up at the house itself a very keen spotted flycatcher darted out from its vantage point on top of a wall to catch flying insects with elegant and accurate pirouetting manoeuvres. What an amazing bird that is; it seems so improbable that they make their way here every year from southern Africa to breed. What a journey for a small perhaps nondescript looking bird. At least the martins, swallows and swifts make their epic journey each year in huge clumps and look capable of incredible feats of airmanship, staying airborne for weeks on end. Birds like that perky flycatcher and its musical warbler fellow travellers look incapable of such a trip, but thankfully they make it every year. They clearly feel at home in the manicured grounds of Penshurst.

I’ve also seen notable birds also at Emmetts Garden, around Darwin’s garden at Downe, Hever and Chartwell, despite the heavy footfall. That seems counterintuitive. My guess is that despite the constant pruning and tidying, these birds find more nesting places in the medieval buildings than in neighbouring areas. They are also drawn by these historic plots’ long-established water features. Then there are the old fruit trees that are maintained out of respect for tradition. Certainly Penshurst does a good job of keeping some of its superb garden quite wild with an orchard and unkempt grasses. Its lovely ancient brick walls must also attract a lot of insects. Neighbouring farms may also use pesticides and over-trim hedges.

So perhaps the heritage gardens, despite their topiary and cultivated blooms, may actually be wildlife oases doing their bit for biodiversity alongside the rewilding projects. Maybe.

I haven’t described it yet but there’s an excellent walk between Tonbridge and Penshurst Place, on a separate path mainly to the bicycles. It would be easy to join with the Chiddingstone route. I must investigate further; there are some beautiful stretches.