The hay fever season brings troubling, breathless dreams; on Sunday I walked too long beside the Thames and fell asleep reading an old favourite. The river and the book and the pollen invaded my dreams and I woke up saying aloud: “That's it! It's all there! We're living it!”

The book was Kenneth Grahame's The Wind in the Willows, picked up because 2008 is its centenary. The bored bank clerk's pastoral fantasy of the riverbank has inspired others from A.A.Milne to Alan Bennett, Pink Floyd to Kenneth Williams. A hundred years on every line still resonates. All human life is here, all politics, all hope and dread: Mole's divine discontent and timid longings, Toad's hubris, the Wild Wood's threats. The Piper still lures us at the Gates of Dawn and vanishes leaving us bereft; the flawed characters are ourselves, their fears our own.

Politicians are easy to spot. Tony Blair may have fooled us into thinking he was a competent, companionable Ratty, with his gleaming coat and twinkly eyes, but we should have identified him much sooner as Toad. Who, in the first instance, was very likeable: “It's never the wrong time to call on Toad. Early or late he's always the same fellow. Always good-tempered, always glad to see you, always sorry when you go!” He beguiled even the Rat into his canary-coloured cart: “Toad talked big about all he was going to do in the days to come, while stars grew fuller and larger all around them.” When the wheels came off his cart project he went for faster, more dangerous adventures with even worse results: “Always somebody else's horizon! O bliss! O poop-poop! O my, O my!”

Where The Wind in the Willows scores over reality, though, is that Toad gets his comeuppance. His friends realise he is all wind, decide to “stand no nonsense”, and refuse him even a final Trimdonesque speech:

“‘No, not one little song,' replied the Rat firmly, though his heart bled as he noticed the trembling lip of the poor disappointed Toad. ‘It's no good, Toady; you know well that your songs are all conceit and boasting and vanity, and your speeches are all self-praise and - well, and gross exaggeration and - and -' ‘And gas,' put in the Badger, in his common way.”

Ah, Badger! Who can fail to identify that dour, gruff, morally upright, unsociable creature in his prudently dug earth? “Badger hates Society, and invitations, and dinner, and all that sort of thing.”

Badger speaks of the long term: “We're an enduring lot - we badgers wait, and are patient, and back we come, and so it will ever be.” I am sure I heard Mr Brown saying more or less that to John Humphrys only last week.

The rest of us -politicians and public - all fall easily enough into the book's great types. Many of us are Ratty, wanting a quiet sociable life messing competently about in whatever serves us as a boat, but too pliable and trusting to resist stronger personalities and their schemes (in the cart adventure, Grahame tells us that Ratty, “still unconvinced in his mind, allowed his good nature to override his personal objections”).

Or else we are Mole, natural camp-followers, enthused by new ideas but then overcome by panicky longings for the familiar, the Dulce Domum. We prefer familiar people, too: in many a region of rapid immigration the dread of the Wild Wood's denizens is echoed daily: “Weasels - and stoats - and foxes - and so on. They're all right in a way,” says Ratty, “- I'm very good friends with them - pass the time of day when we meet, and all that - but they break out sometimes, there's no denying it, and then - well, you can't really trust them, and that's the fact.”

Was there ever a better, briefer summary of instinctive xenophobia? Unless, of course, it's Ratty's other dictum: “Beyond the Wild Wood comes the Wide World, and that's something that doesn't matter either to you or me. I've never been there, and I'm never going, nor you either if you've got any sense at all.”

That suspicion of the Wide World endures: Ratty and Mole are the fretful British electorate in times of globalisation, no doubt about it. There is also a worried underclass of rabbits and squirrels, “a mixed lot”, whose main aim is not to lose their homes or be mugged by stoats.

Yet also within the national genome lurks an adventurous streak, and Grahame acknowledges this too in the the seafaring rat who nearly urges Ratty to join him at Fowey: “We shall break out the jib and the foresail, the white houses on the harbour side will glide slowly past us as she gathers steering-way, and the voyage will have begun! As she forges towards the headland she will clothe herself with canvas; and

then, once outside, the sounding slap of great green seas as she heels to the wind, pointing South! And you, you will come too, young brother; for the days pass, and never return... take the Adventure, heed the call, now ere the irrevocable moment passes!”

Oh, we're all in there. Those singing siren songs to Crewe & Nantwich electors should keep the book by their side. It encapsulates everything: our yearnings, our fears, our contradictory loves of domesticity and adventure, our tendency to follow a romantic Pan or banner-waving Toad, our fear of knife-wielding stoats and weasels, our longing for a dour heavyset Badger to come and sort everything out.

And, I suppose, our hope that David Cameron might turn out to be a Ratty (“with his neat ears and silky hair”...well, maybe) who will take us on nice picnics and not overturn the boat.

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