However, a little further on in Spickett’s Lane there are several more plum trees festooned with fruit of different varieties. The first of these are small and crimson when ripe, and quite deliciously sweet with an intense flavour. Juice dribbles down my chin. There are damsons, small and black and too high to pick without a ladder, more small yellow fruit and one in-between. On the other side the lane, the blackberries are not ready yet, but will be black and luscious in a couple of weeks.

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I turned right, past the piggery where a few Oxford black-and-tan rare pigs remain, snoozing in the gentle morning, then round the edge of the bean field down towards the river. Waddesdon Estates farm this land and, as part of their Environmental Stewardship Scheme, all of their fields have a wildlife strip around the edge where wildflowers (weeds) prosper and bees and butterflies dart and settle in their search for nectar. A month ago, when the wildflowers were at their best, there were lots of butteflies: meadow brown in particular, common blues and small whites, green-veined whites, red admirals, peacocks. Now these are fewer, but they are still to be found along with a gatekeeper (small meadow brown) or two.

There are rustlings in the high, scrubby hedgerow and I hear some squirrels having a fight, squeaking and jumping about but see nothing. I cross the stile that penetrates it and step into a cow pasture with a wooded, watery drainage channel on my left. This is where newts, grass snakes and waterfoul skulk and a source of dragonflies and damselflies, and I see a large one zoom over my head, too fast to identify.

There is a brown bull with broad shoulders and a deep chest right ahead of me, on the footpath route over the field, and I approach with a little caution; but he is quiet and docile as I skirt around him. The air is fairly quiet now where it was alive with birdsong a month or two ago, but there are birds about. A buzzard circles up on a thermal, but doesn’t come close enough for me to see his colours. There are a lot of crows in the sheep meadow, and rooks in the wood at the top of the field, and an owl box in the tree near the cattle bridge where I saw a tawny owl last march. And there are the ubiquitous pigeons, flapping away noisily as I approach, and sparrows.

The cattle bridge crosses the River Thame, and a pause to see if I can see any fish in it’s fast flowing water. The reeds are varied and luxuriant and a shy moorhen pokes it’s head out of them but doesn’t emerge this time. A couple of cows gaze vacantly at me as they chew their cud.

I cross a gate and a stile, entering the Eythrope Estate, home of Lord Rothschild, who also owns the entire Waddesdon Estate.

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Again there are wide, wild field borders, and as I skirt the field through longish grass, I see more white butterflies, and a couple of brimstones that look like a leaf when they stop to feed.

Above, buzzards and red kites glided under the blue sky and seemed to be gathering over the hill to the north: perhaps there was some carrion there.

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As I walk, young pheasants suddenly burst up from the wheat and tall grass, flying further down the track or running into the scrub for cover. These are being bred for the shooting season that starts in October, but that is not the only doom that awaits these tasty game birds!

From only a few feet away, a fox springs up from the wheat where it had been lying in wait to catch a pheasant dinner, and runs off disconsolately through the golden crop.  It is amazing what a wheat field conceals: along with the fox, and the pheasants, various small birds would suddenly appear, wings flapping at great speed in their panic to reach the nearby trees.

I come to a wider area of wildflowers still in bloom: this area would have been planted with a rich variety of native species as part of the Waddesdon environmental work. The air hums with honey and bumble bees, many different flies and some small blue butterflies. This is a sound I hear too seldom these days where it used to be the norm on a summers day. It is the sound of nature at work in a healthy countryside and alien to blank squares of monoculture. This land is intensively farmed, but space is left for natural ecosystems to work and it’s health protected from chemicals and machines.

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I stop to enjoy this buzz of life, then as I turn, a hare bursts out from the undergrowth a few yards away, and disappears into the hedge. About half a dozen kites are still circling in the air high over the hill, and a sudden birdsong bursts from nearby trees.

I leave the Waddesdon land, and climb through a meadow, then over another stile onto a neat and tidy field of rye grass: green and even and silent. The field edge has been mown, and it is empty of flowers, insects or any interest and the contrast is staggering.

We have turned much of our countryside into an aseptic monoculture which has been profoundly destructive to the diversity of nature in the British countryside. We have cut down hedgerows, ancient forests (over 80 percent have dissappeared this century), poisoned waterways and tried to turn the land into a factory floor which, for sterility, this field resembles. The terrible thing to me is that we have forgotten what the countryside should be like, and was like until very recently. The land along the Thame Valley shows that we can have both efficiently produced food and healthy natural ecosystems.

Waddesdon manages to farm profitably and efficiently, and because the people running it leave some land for nature and take care how they use modern technologies, after only a few years there is a resurgance of a diverse and healthy countryside. This creates a balance that protects crops, a balance that is destroyed by over-use of expensive chemicals and over-intensive practices. The result is that many of our species of  birds and mammals are on endangered lists, and the countyside is often silent and boring.

My walk took me less than two hours, and in that time I have come across dozens of species, and been inspired and amazed by seeing the web of life at work. We do need more of it throughout our country, and it is us, all of us who have to make it happen realising that it is our health and quality of life that is at stake, and doing what we can to understand and restore our countryside.

I rather subscribe to both the Gaia theory and to the idea that humanity will have to control it’s population at some point. The Gaia theory is that the Earth will tend to keep our atmosphere and biosphere constant within narrow limits until a certain point when, if the pressures on it continue, it will change rapidly to a new status which could involve dramatically different conditions across the globe. This would be cataclysmic for today’s life forms and only the most hardy would survive to rebuild.

The amount of carbon dioxide in our atmosphere is a pressure on the global system that could push it towards a ‘Gaia shift’, and it’s increase since the industrial revolution has been alarming and is still gathering pace. If you compare it to a chart of population growth, the two are very similar.

The effects of the increase in CO2 include storing more of the sun’s heat in the atmosphere, thus ‘Global Warming’, but we are also seeing an increase in the acidity of our oceans, which means that it is more difficult for organisms to use CO2 to make their shells, and can result in shell materials being dissolved. To put this in context, calcium carbonate shells and reefs built by tiny marine organisms account for all the chalk and limestone on the planet, and there is a great deal more spread through the oceans as living or recently dead organisms. If this material dissolves, it realeases yet more CO2 into the atmosphere and prevents more shells being made. If you think this through, it is a vicious cycle and not the only one we face.

The point is, the more CO2 we release by buring fossil fuels, the more is released from other sources around the planet. And even if humans were not responsible for global warming, even if it were true that we are going through a very rapid ‘natural’ cycle as some believe, then surely it would make sense for us to reduce our global warming gas output so as not to exacerbate a dangerous trend?

We cannot escape the logic that the more people there are, the more CO2 we will release by burning fossil fuels, an effect that will be magnified many fold as they all aspire to be richer and consume more.

There is much that we can, and must, do to mitigate our environmental impact, and this starts with each of us as individuals. According to Jonathan Porritt, the UK Government is very comitted to action on climate change and to helping individuals and communities play their parts whilst the government handles things at a national and international level: let’s hope so!

Internationally, the Copenhagen conference in December will be key in moving things forward; in fact in instigating a step change in the way governments behave.

We must make a start on working out how to control population growth, which does not mean that we put on hold reducing our energy use and environmental footprint: in fact that has to be where we start because it will take effect much more quickly than any population measures.

This all comes back to my “Death to The Environmentalist” blog: we can no longer be ‘greens’ and the rest but must pull together to stabilise the situation now as far as we can. People who believe that there is a problem need to work in concert, bringing their different expertises and energies to bear on its many facets, including global warming, biodiversity, habitat protection, equalisation of resources and population control.

Dr Lovelock is in good companyas Sir David Attenborough, Jane Goodall and Jonathon Porritt have all said that we must address the population issue.

To take a one-sided view and work as if the other stake-holders didn’t have a case is a recipe for disaster in the form of a Gaia shift.