At this point the stony riverbed is no more than a metre wide along which the bedrock forms a series of shallow steps over which the water flows in cascades, like a glittering staircase. Above here the river branches out into a network of small streams, any one of which could be called its source. Disturbed by my arrival a grey wagtail bounces away downstream flashing its chrome-yellow underwear.

I have set out this morning to walk down the Afon (River) Lliw, having been given a lift close its source. At this height it is no more than a shallow-v cut into miles of rough and rolling pasture, brushed with the bleached tops of soft rush and mapped by weathered stonewalls. It feels high-up-above here and there is an exhilarating sense of space. A cocksure wheatear flirts his tail from a wall top as I pass. Sheep are scattered across the landscape like confetti and in one place there are cattle – an uncommon sight in the uplands these days. Trees and bushes are non-existent, save one: an ancient and frail looking hawthorn permanently bent by the wind, which still flowers ‘defiantly’. Feeling my age, I note the metaphor and tip my hat to the tree. I have mixed feelings about this landscape: on the one hand there is the grinding attrition of the vegetation from centuries of stock grazing, which is personified by the single derelict hawthorn, and on the other hand the sheer magnificence and freedom of just being here. It is a fine Sunday in May and if I meet anybody else all day it will be a surprise (I didn’t).

Half a mile downstream I come to an abandoned, but tidy, stone house in the middle of nowhere. Barring the two sturdy sycamores at its back (the signature trees of these hill farms), there is no longer anything to anchor it to place. The roof is still good and the front door key is hanging up – on the outside! In the downstairs room is a scatter of wooden shearing stools; a cracked mug on the cast iron range and some rusting tinned food in a cupboard. Upstairs two desiccated swallows lie on the dusty floor – they must have got trapped inside, somehow. Perhaps this house was always a ‘hendre’, a shepherd’s summertime cottage, but it is a vivid reminder of how many more people lived in the uplands 150 years ago. Within sight of here, at Hendre Blaen Lliw, my son’s friend Owen has just moved into what must surely be, at 1500 feet, one of the highest inhabited houses in Wales. A young man on his own with no mains services takes a certain kind of resilience, especially in winter, but I suppose he was born too it as his family farm much of this wild land.

Below Blaen Lliw the river widens out a bit, and because water levels are low in this dry spell, a layer of blotchy pink stone the colour of drowned flesh has been exposed below the usual boulders dark with moss. A common sandpiper flicks away downstream on stiff wings piping loudly. I’m pleased to find they are still on the river. One or two rowans have begun to appear on the riverbanks and in the top of one, about fifteen feet up, is a tidily refurbished crow’s nest. I contemplate climbing up to see if it contains eggs or young, but think better of it. There is something reassuringly domestic about this homely nest in such a bare, windswept landscape. At the same time it seems an unnervingly exposed place to incubate eggs, and feed chicks. A red kite wheels over the river, crossing the valley with barely a wing beat. We met Stephen (Owen’s father) on the way up and he told us it had been around for several weeks, probably feeding on the afterbirths at lambing time, so providing a useful clean-up service. To my right about a quarter of a mile away the ground rises steeply towards the highest ground. There is heather on these slopes, an indication of less grazing pressure from sheep and a scatter of fifty or so young rowans reinforce the point. Sheep numbers in the upland have been reduced since an historic high in the 1980s and now, on some less accessible slopes and rocky places, the beginnings of new woodlands are springing up.

Where the valley widens out there is a sizeable bog and it is hard going across the lumpy cotton grass – which is just beginning to wave its white flags. Towards the middle are waist high clumps of tussock sedge, a sure sign of the wettest area. Apparently the ‘tussocks’ of these enormous sedges used to be trimmed into hassocks for kneeling on in chapel years ago. A grasshopper warbler is reeling off its drunken song somewhere out in the rushes and nearer at hand a reed bunting is picking out a much more hesitant tune. As the wind sighs across the bog I am filled with gratitude in the solitude of this wild place.

The weird thing about waterfalls is that you can’t hear them from upstream until you are almost upon them. In this case the Afon Lliw plunges over a shelf of hard rock just above Buarthmeini; seventy feet of crashing, glittering water that orchestrates every other sound.   Set amongst rocky hillsides studded with birch and rowan trees it is wonderful sight. In the south of Britain it would probably have a car park and picnic site; up here there isn’t even a path. Nobody bothers with it.

These birches are the first I have seen since starting out this morning and they provide a song post for my first willow warbler – so neatly pointing up the link between habitat and species. Clambering across the water-scoured rocks at the top of the falls I find bluebells in deep cracks and some violets the texture of purple velvet. There is even a straggling thyme plant clinging on precariously – how does it withstand the river in spate? Getting down the side of the falls is a struggle as the steep, rock strewn ground is knee-high with heather and clumps of moor grass. I experience my only moment of fear all day, this is leg-breaking terrain and there is no phone signal here.

Below the falls the air is thicker; it is sheltered and intimate compared to the wide-open uplands above, where I had felt like an ant creeping across the landscape. This bit of land beside the river is fenced out, perhaps to protect the sheep from the danger of the falls, and it has become lush. There are hawthorns and hazels and even a young sycamore in the proto-woodland. Marsh marigolds and wood anemones are flowering beneath the trees and a lizard slips away from my boot. A singing blackbird conjures the warmth and security of village lowlands. The absence of nibbling sheep in this sheltered place has released the land, allowing it to move towards its wooded climax.

A hundred yards further down river I stumble upon a ruined farmstead huddled beneath a rocky bluff and screened by ash trees. It is of Lilliput proportions – the house no bigger than a modern lounge. The roof has long gone and ferns and moss soften any sense of absence. The window sockets, chimney and a slate threshold are still intact. Out front are a barn, sheep pens and several small meadows mapped out by crumbling stone walls, some of which are muffled with cushions of silver-grey moss a foot deep, like insulation against history. The whole place is slowly sinking back into the earth from which it arose. Yet 150 years ago there would have been a family here with, no doubt, multiple children crammed into this modest house. Whenever possible life must have been lived out of doors. Oats would have been grown, bread baked, cows milked and cheese made. They would have laughed and quarrelled, hoped and feared like the rest of us. Most of all they would have worked, the endless physical work that is the lot of peasant farmers the world over. A sense of community and interdependence amongst the handful of farms scattered through the valley, coupled to strong traditions and a sense of humour would have helped temper the hard labour. Expectations must have been very different then as most people rarely left the valley and the edge of their familiar world was probably within a ten mile radius of here. With just a little more phone signal I could find out what is happening in Beijing right now. Sitting here on a mossy boulder in this slow moving place that seems totally absurd.