Everyone else seems to have been there. Already, at a dozen years old, it has had its own exhibition at the Garden Museum. The Jardin Plume, just east of Rouen, was our first stop in a week of inhaling French gardens.

The critics are right: the Feather Garden is a breakaway. A flat field and the remains of an orchard calls on the uncompromising French tradition of open-sky formality (think of Vaux le Vicomte) and brings it right into the eco-present of undulating grasses.

Convention seems irrelevant here. You enter through a mere gap in a hedge in a field – into a modest nursery. You pay your modest fee and find yourself guided by immaculate (but undulating) box hedges into a jungle where the flowers and grasses meet above your head. You are eyeball to corolla with familiar and unfamiliar flowers; here a pennisetum, there a verbena or thalictrum or even a hydrangea. Grass cut paths set the structure, then narrow hard paths induce you into a world of creatures green in tooth and claw, where touches of colour (flowers often tiny in relation to their supporting plants) merge into a pointilliste picture. Those dabs of red are a six-foot sanguisorba, the purple rockets a veronicastrum taller than any you have seen and the soft mauve splashes a soaring phlox.

Perhaps it was the summer of endless rain that had made perennials abnormally tall. But that is only the prologue; there are many chapters to come.

The main body of the garden is a series of plots of tall grasses (here and there a clump of meadow flowers) separated by smooth mown paths. They stretch away with only a few apple trees to offer your eye a stopping place. At Vaux le Vicomte, I remember (the scale is different, but the concept similar), the immense floor is not compromised by trees of any sort. Here your eye is offered a focus and a resting place by a square mirror of water, unplanted and unadorned, in the foreground. Around the broad parterre stretching to the horizon are the classical enclosures; potager, flower garden, cloister garden, all reinterpreted for a post-impressionist consciousness.

Nor is everything as graminaceous as the name implies. The cloister garden is entirely grassy: just huge miscanthus clumps forming a swaying hedge around another square mirror pool. But the Summer and Autumn gardens are more or less formal adjuncts to the farmhouse where straight box hedges enclose flower beds in an almost traditional way – until you look in detail at the choice of flowers and the way they are grown.

The potager is the most traditional, in combining vegetables, fruit and flowers in a way we never seem to master in this country. Some of the colour-play here is subtly contrived: different phloxes, for example, with pink clematis and the contrasting cool lemon of Oenothera odorata. Other passages are just plain jolly polychrome.

It didn’t dawn on me until we had been wandering in delight for an hour that we were being seduced by the most fundamental game in gardening, from classical times to our own. It is the interplay of the precise and the nebulous, the architectural line and the wandering spray, the box hedge and the flowering grasses, that defines the art.

The Jardin Plume: interplay of the precise and the nebulous

Waterflame at Houghton Hall

To Norfolk to see the walled garden at Houghton, having heard many excited reports. We were not misled: it is one of the most original and stimulating creations of recent times, a complete reinterpretation of a classic model, to be compared with the Alnwick extravaganza. It feels far more personal though, intimate and thoughtful. You pass from compartment to compartment in a state of heightened awareness rather than wide-eyed awe.

The Marquis of Cholmondeley has dedicated his creation to his grandmother, Sybil (née Sassoon), who reigned at Houghton for half a century. Many years ago we had the good fortune to be shown around the palace (the only word that fits it) by her. She apparently enjoyed giving tourists her personal tour.

Indeed we had the same experience at Hardwick Hall, where the formidable dowager Duchess of Devonshire lay in wait for tourists and gave them unforgettable moments of living history. When she was a girl, she told us, she watched the housemaids taking down the tapestries and carrying them to the ponds in the park to tread them. Now, she said, they have to go the V & A for cleaning: absurd.

But Houghton. There must be twenty rooms in the walled garden, and no repetition except in the immense parallel herbaceous borders of the central alley, a bravura performance, edged with catmint from end to distant end, from vineries to a Bannerman fantasy: a log temple, its pediment a forest of antlers.

The Bannermans also designed the sunken fountain in the centre of the complex,immensely pretty, pink and white rose garden. You sit within a circling flint wall engulfed in the sound of water, an interpretation of the classic grotto in the open air, among roses.Six foot high lilies lean out at you from box-edged squares. Huge paeonies do the same. The herb garden, the vegetable garden, the orchard, the croquet lawn (notice: you are welcome to play) are all included in the pattern, and the playing and punning with plants is inexhaustible. The Waterflame is already famous, but you still blink to see a fountain with flames on top. Nor is the walled garden, of course, all there is to see. The deer park seems to follow a model of its own, somewhere between a park and a forest, with grand trees at a fraction of the usual spacing. I was reminded of Uccello’s haunting hunt in the Ashmolean.

I don’t know whether there is a historic rivalry between Houghton and Holkham, but I wouldn’t be surprised. Are the Cokes of Holkham tuning up for competition? Their vast walled garden is showing signs of vigorous renewal, too.

I’m intrigued by the fact that parts of our coastline can become cults – at least for a while. Not only the coast, of course: we hear plenty about the Cotswolds, and two hundred years ago it was the Lake District everyone talked about. In the 1930s Frinton was the height of chic. Then it was St Ives, and now the north coast of Norfolk is having its turn. Burnham Market has been called Chelsea sur Mer – despite the fact that none of the many Burnhams, nor their neighbours, are actually on the sea. The sea has retreated, leaving long flats of saltmarsh, sand and seabirds, ideal for walking off lunches of Cromer crab and admiring the hundreds of windmills that have suddenly populated the shallows.

Norfolk, however, is naturally rich. Fertile fields are its dowry. Why else would two of England’s most magnificent houses crop up in such unexceptional landscape? Houghton and Holkham are not only the best examples of 18th century showmanship, they are both still very much in business. Their huge estates (and that of Sandringham next door) give coherence to endless acres of well-farmed land and well-dressed forest. Neither, on the other hand, was distinguished for its gardens – until recently.

‘You garden with a light touch’ said a knowing visitor the other day – appreciatively, I hope. Could she have been referring to the complementary campanulas, the aleatory alliums, the volunteer violas and random ranunculus that meet your eye wherever you turn? ‘You leave things in; so much nicer than taking them out.’

I do take them out. I’ve been barrowing opium poppies to the compost for weeks now. The idea is to let them show a first flower or two, decide whether it is a good colour or not, is fully frilly or otherwise   desirable, and pull up the ones that have no

special quality, in the hope of improving the stock. After years of doing this I admit we aren’t getting very far, but I enjoy the process.

The thing to remember is what comes out easily, like the poppies, and what leaves roots in the ground. You can enjoy an allium, even into its seed head phase, and still get rid of it. Not so an invasive campanula. And violas are the devil to do away with.

But most of the pulling up at the moment is what I think of as busy lizzies of various kinds. I’m not clear about all their identities; only their vigour and the distance they can chuck their seeds. You merely look at the watery yellow-flowered kind, only a few days old, and it looses off a petulant scatter of seeds. It’s lucky I enjoy weeding so much.

My son in law brilliantly described an old house we rented in Wales as representing a hundred years of botching. An archaeologist might have loved the rich evidence of ages past: former décor in curling wallpaper and peeling paint, superseded plumbing, no longer functioning window catches, proof that every room had been converted (but not quite) from some former use.

I am an ace botcher myself. My family calls in a professional if anything needs doing beyond changing a light-bulb. They can manage that. A garden, unless I’m kidding myself, is more forgiving. How do you recognize botching unless you know what was really intended?

I don’t mean gates tied up with baler twine or roses on old bedsteads. That was the scene here forty years ago. The style may well be having a renaissance in certain gardening magazines. Old bikes, jam jars, that kind of thing. No, with me it is largely a matter of tools.

Some mornings or evenings I march into the tool shed full of resolution, sure that I know just what I’ll need. Fork, spade, saw and shears, trowel and twine go in the barrow. I reach the scene of operations and set to when I meet a plant that needs a stake. No stake. Do I retrace my steps? I look around for anything that will serve. I even tie one plant to another, resolving that I’ll be back with a stake very soon.

Most mornings and evenings I saunter out with nothing but my secateurs in their leather holster. They are black steel, forged in Japan, with no fancy business of pretty handles: the gardener’s six-shooter. I don’t find many jobs they won’t do – more or less – from light weeding to banging in nails. They are a precision instrument with a fine edge fit for bonsai, but with a wristy twist they will lop a one-inch branch.

The garden is full of evidence that I’ve surged through, half-doing a hundred jobs. The mercy is that no one but I will know, and I’ll have forgotten.

Don’t you sometimes speculate about the women whose names adorn some of the most voluptuous roses of the summer? They are nearly all French. I wish we had their portraits. Did Madame Grégoire Staechelin blush (or droop) like her namesake rose? Was Monsieur Staechelin the bristly buttoned-up individual his name seems to suggest?

Can you form a mental picture of Madame Lauriol de Barny? A plump and pleasing, rather artless young woman, I rather fancy, apt to put her foot in it. Madeleine Selzer (marital status unknown) was self-evidently a fizzer. La Séduisante (name unknown) needed careful handling. And what does  Madame Isaac Pereire conjure up for you? I see a severe and stately lady in black holding her luscious magenta cabbage of a rose at waist level to avoid suffocation in its dangerously sweet perfume.

The ladies parade before us, all décolleté and bustle, with no shortage of artful ribbons. Are some lovesick? Is Madame Bovary an unchristened rose? ‘When first open on a cool clear day’, says Graham Stuart Thomas, ‘Madame Pierre Oger is of a soft warm creamy flesh’. The Nymphe émue even lets us see her blushing thigh.

We know that Caroline Testout was a couturier from Grenoble, and that Madame Sancy de Parabère was a general’s daughter and lady in waiting to the Empress Eugenie, who would not have been amused by her bothy moniker of ‘Saucy de Paramour’. Nor, I fancy, would Madame Alfred Carrière, patroness of the loveliest of pale blushing climbers, have answered happily to ‘Mad Alf’, the name I heard a gardener give her.

In this rosiest of seasons, in the first warm days after unending rain, the fleshy fragrant presence of these women is inescapable. Climbing Lady Hillingdon is pressing her soft orange globes against my bedroom window. Surely this can’t be, as Robin Lane Fox tells us, the Lady Hillingdon who closed her eyes and thought of England.

I may well lose more readers through my enthusiasm for weeding, annually expressed, than by being boring, repetitive, out of touch, living in the past and my many other weaknesses. I can’t help it. Weeding for me is the epitome of gardening; the time when every move is decisive and, to use that corny phrase, you can see where you’ve been. Planting is the other supreme gardening pleasure; the satisfaction of settling roots in soil always gives me a glow. But planting is the work of moments, while weeding is a long drawn out pleasure, always (at least in this garden) available.

Why do I love it? Because it calls for total concentration. As I stoop or grovel in the border (or anywhere else where muddle is taking over) my eyes must be fully focussed. What appears at first an agreeable jumble of green shapes becomes progressively clearer as I start to edit it. There are in-your-face weeds: a dock or a nettle makes no attempt to hide. There are insidious weeds that blend with the background: violas and little balsams that can lurk while they multiply. And there are wily, snaky weeds that infiltrate under disguise.

Just now it was bryony in a mahonia that had reached the top without my noticing. Always and everywhere it is goose grass, spreading out from a root no bigger than fuse-wire to launch its sticky tentacles into whatever it encounters. It took me five minutes of patient groping, using its rough texture on my fingers as a guide, to disentangle one plant of it from a patch of Geranium.

I have learnt a few tricks, leaning over the herbage, breathing in its evocative  variety of smells. The first is always to use a fork – not always to prong with, but more importantly to lean and balance on. It’s the rule of ‘one hand for the ship’: right hand on the handle for balance, left hand for reaching down and out. You can reach improbably far into a border if you are a tripod.

There are plants that never seem to need weeding, but they are rare. I rarely find weeds in established clumps of hemerocallis, and the big leaves of Phlomis russelliana are exceptionally effective at covering the ground. Some geraniums are hard for casual weeds to penetrate, but nothing, of course, smothers bindweed. Nor I fear is there any pleasure in it. In fact, I exclude bindweed, couch grass and ground elder from my enthusiasm. So perhaps I am not so different from other gardeners after all.

The camera zoomed in from an improbable height above the royal Bentley purring back from St Paul’s. On the way it encountered the branches of a plane tree and saw right through them, through sadly deleted leaves and sagging shoots, in a way you never can through the canopy of a healthy tree. London’s planes are sick, some of them very sick, and the prospect of their decline is too dreadful to contemplate.

Is it a new disease, as some suggest, or the occasional weakness that strikes them under peculiar circumstances ? Does it relate to a hot dry early spring followed by a long cold and wet April and most of May – and June? I used to worry about an alley of London planes I planted in central France; in some years, particularly in wet springs,  their new shoots died back as we see them doing in London now, but 20 years on they are robust young trees.

Central London has been verging on a monoculture of planes since its elms died nearly forty years ago. We forget how important they were. Many of the finest trees in Hyde Park, for instance, were field elms, with their crowning fans of branches, their flaring skirts and their pale gold leaves almost to the end of the year. London has few oaks and not nearly enough limes. The resilience of the plane, it resistance to pollution as well as its majestically graceful canopy and its huge reptilian trunk, have given it the status of the London tree.

The local authorities have been imaginative in the past few years with their street trees. We see rowans and alders, ginkgos here and there, many hawthorns in the parks, and so many Chanticleer pears that we have to hope they are resilient too.

But the mainstay of our parks and squares is the London plane. Since the 18th century it has defined the landscape of the West End, historically and practically. It is strange that a sterile hybrid should become the climax tree of the London forest – and should certainly be worrying us now. We desperately need to find a treatment to keep them going.

I remember my moment of disillusion. It was in Berkeley Square. An enormous shiny car came round the corner of Bruton Street pretending to be a Rolls Royce, but instead of the familiar silver Parthenon and its floating goddess its radiator was like the front of an American truck: a bloated travesty of a classic design.

The whole vehicle was gross; engineering grace had given way to gigantism. (I heard to my delight that the makers had to reduce the length of the thing for Hong Kong to avoid it being classed as a lorry).

The same feeling of revulsion hit me again in my favourite London space, the Green Park, the other day when the wraps started to come off the new memorial to Bomber Command. It looks as though someone was using someone else’s credit card in the

Haddonstone catalogue: a hundred yards or so of pseudo-classical columns supporting a useless architrave. In the centre will be a bronze group of the heroes it celebrates.  Apart from the question of waiting 60 years to mark a tragic victory over a country now an ally, why do we need the exceptional emphasis of this giant colonnade?

The western gateway to London, Hyde Park Corner (Apsley House was once known as no. 1, London) has become a showroom for ever-bigger memorials. Where once a single statue represented a hero and sufficed for a regiment, we now seem to need a quarter of an acre of masonry. The New Zealand memorial just across the road has sixteen black exclamation marks where one would have been eloquent and dignified. The Commonwealth Memorial Gate awkwardly straddles Constitution Hill with undistinguished masonry, like a pedestrian crossing with an inflated ego. Anywhere in Monument Alley, which now encompasses Park Lane as well, seems fair game for this new branch of the building trade.

You can cite the Albert Memorial, of course, as pretty extravagant. But where are we heading, with the idea that bigger is better? Think of the Mini, and shudder.