Autumn had come late to the Downs that year and the leaves hung tawny and bleached green on the trees. The day was still; a minuscule shift in the air currents brought them down around us in eddies, as we walked – Frank Beresford and I – up a flint track on a pale November morning.

Frank Beresford was a retired schools inspector from West Wickham. We had met just once, that summer, at the Lithic Studies Society in London, at an afternoon talk on the artefact-logging systems of the Portable Antiquities Scheme.

We were the kind of audience that shuffled in and nodded where necessary before fixing on the speaker or our feet. But that day the president, in a burst of embracive enthusiasm, asked that we each introduce ourselves and declare our area of interest. When my turn came I kept it brief, telling the group about my fieldwalking, the flint tools I had logged and the Neolithic settlement I had roughly mapped on the upper slope of a river terrace on the North Downs. What might have been truer to say was that I was a 54-year-old woman with a rock problem, but it was not a confessional, and anyway, we all had our issues.

Frank Beresford’s, it turned out, was hand axes. Frank was writing a report on the Palaeolithic tools of the Upper Ravensbourne valley; an axe had been found locally to me by a 19th-century antiquarian, and Frank said he’d be keen to join me fieldwalking, should ever I happen to be over that way, to get a feel for the landscape.

And here, some months later, we were.

I had grown up on these Downs, on the opposite side of the valley. I still live in the village where I was born, which is mostly happenstance and suggests a continuity that’s by no means true, but that is one of the great blessings of my life. From my house I can see fields and the small copses that stretch away to the wooded ridge that defines a wide horizon. I walk the Downs all the time, but not these woods and fields in my immediate view, which are farmland and mostly out of bounds.

The track we were following – a hollow way worn to mud and stone by footfall and washed deep in the middle by rain – runs at right angles from the valley floor up to the ridge, after which it doglegs down into the next valley. The fields on either side of the track have no paths across or round. A warning to trespassers on a sign close to the entrance stile and, again, farther up the track, must have put the local dog walkers off. The couple of times I’d ignored the sign and walked the fields after ploughing, I’d turned up nothing for my trouble. Not even a decent nodule. I’d noted them as archaeologically sterile and geologically dull. Anyway, some places just feel wrong if you’re alone. It was years since I’d walked this way, so I was happy to be exploring afresh in Frank Beresford’s company.

The find spot of the axe Frank was studying was a small chalk quarry near the southern tip of the wood where we were headed. Frank was certain it came from the clay overlying the quarry and was unearthed as estate workers dug down to get to the chalk to use for fertiliser or to make lime for mortar.

The axe was now in the British Museum stores – part of its vast back-room flint collection. Frank showed me a picture on a printout. It was magnificent. Deep-toffee-coloured flint had been knapped – that is, shaped with a series of carefully aimed hammer blows from another rock or antler piece – into a round-topped kite-shaped axe that would fit into the grip of a large man’s hand.

Its date – based on others of its type – was around 420,000 years Before Present. It meant that no Sapiens had made it. The hand that knapped the tool belonged to Homo heidelbergensis, a species of human that lived 800,000 to 300,000 years ago – becoming extinct around 100,000 years before the Sapiens lineage emerged on the African continent.

I have held tools not touched since they were discarded 5,000 years ago in the late Stone Age. I have gathered flint flakes struck by Neolithic knappers on the banks of long-dead rivers. I’ve found fossils worn smooth by ancient human touch. But I have never held a tool made by another kind of human. I asked Frank if he’d had the axe out of its storeroom case. He said he had. I wanted to ask what it felt like to have it in his hand, but that was at once stupid and personal. Stupid because it probably felt like nothing; personal because if it did feel like something, that was between Frank and the hominin.