I’d like to think there were editorial clashes; Katharine Briggs, in her mid-seventies and a towering authority on British folklore, pushing for the inclusion of more fairy stories while Russell Ash, fresh off Fortean Times forerunner Man, Myth and Magic, arguing the case for quirkier tales of magic. Robin Gwyndaf Jones roaring “MORE WELSH!” Of course this is not how it would have happened, it’s fanciful nonsense. In reality, it would have been  compiled centrally, at the UK offices of that most unhip of institutions the Reader’s Digest, from the works of the impressive list of contributors. After all, even with such a line-up who could argue what is more valid to be included in a book like this? What is the bar for entry?

Put it this way – if you were to revise and update this book for publication today, what would you lose? An entry that seems a little generic, that just repeats, say, the “White Lady” motif for a spooky old house. Well, that seems like an obvious loss, doesn’t it? But further thought would tell you that it’s vital to keep that sort of thing. It may not add much to the book in terms of additional reading but it tells you a lot about the way folklore spreads, reproduces. What is important in the national psyche. We see the same ghosts on a hundred different staircases. Hair sprouts from a dozen graves. Every church and every pub in the country is connected by a vast web of secret passages.

The wonderful thing about this book is how broad it is, how inclusive. Its magpie sense of what’s important. Everything is important. The smallest thing, the silliest detail, all of it. It’s as if, given a wide remit and a vast, almost-guaranteed circulation, the editors and writers wanted to get as much as possible in to the book. We have to be glad they did; this was published in 1973, mere moments before the world got so much smaller.

When mass communications link us all together much more minutely, folklore has less space to grow. Legends become generic, though that’s no slight on urban legends (The tracking and tracing of those is a thing of beauty in its own right, and the modern equivalent of this book remains rummaging through Snopes with a dozen open browser tabs). The problem is that the stories and beliefs catalogued in this book have been developed over years – centuries, in some cases. Oral tradition, local history, folk beliefs that will almost inevitably die off as we become more, for want of a better word, sophisticated.

I don’t wish to sound maudlin, mourning a lost world and berating our modern one. Not at all. The world moves on, mutates. Pockets of unreason will exist as long as we have an imagination, and it’s good to have someone taking notes. Which brings us back to the book, sorry for the detour. I believe the last specific thing I said about it was that it was published in 1973. As far as I can tell, it never got a second print run. It sold and sold and then sold out and that was that. It found its way into who knows how many households as Reader’s Digest was pretty much at the height of its popularity. There it sat on all those bookshelves and, quite unexpectedly, shaped a generation.

I expect some adults read it. Of course they did. They bought it, why wouldn’t they? It would be an interesting sort of book to read, some folk history a bit of research on the traditions of the country. Yes. Very jolly stuff, the kind of book one can dip into of an evening and find something interesting every time. They’re not the important ones here – sorry, Boomers, you’re not the centre of every story. Somehow, maybe it was always kept on low shelves, maybe there was something about that cover with the Dorset Ooser, maybe the layer upon layer of weird history gave it its own curious magic but somehow over the years that passed, as it sat quietly in the dust, it called to the children of the household.

Ask anyone of my generation who knows this book and they’ll tell you how they spent hours poring over it. Flipping from entry to entry, taking in the illustrations, letting it seep into their malleable young mind. The entries (which veer between lightly humorous, matter-of-fact or near poetry depending, I assume, on who wrote it) showed these young things, their heads full of Spangles, spacehoppers, white dogshit and Doctor Who, a world of goblins and devils, dark bargains and strange rituals just outside their doors. This was Britain transformed into a country of deep mists and moonlight as alien as any Tom Baker might encounter. Its bitesized curios and spooky, out-of-time illustrations hooked us gently. To a second generation raised in the Cold War it offered a vision of our country before we could turn on the lights to banish the dark.

Those of us who held on to that idea might now scoff “well of course. It’s Britain. That’s how Britain is” which is true, but we didn’t know that then. All we had were hints. Playground whispers. Local stories. There’s not a person alive who, faced with such a book, doesn’t first turn to the area they live. Confirm that It’s Not Just You. I crept through the pages to find Leicester, to see if Black Annis made the cut. She did, right enough, with a suitably terrifying picture. That was it. The first toe placed gingerly in terra incognita.

Belief flowed; we grew up as adults bewitched by faerie rings, captivated by hill carvings, unable to pass a standing stone without Instagramming it, researching its history on our phones as we do so. Psychogeography boomed as we came to adulthood, hauntology flowered as we graduated, drunk on Derrida and the end of the Cold War (and actual drink). I don’t want to get too second-year-sociology-student about it, but the fall of the Iron Curtain gave us a psychological space that we were yet to fill with international terrorism and so in came the preoccupations of pre-Industrial society. While we read Prozac Nation and grappled with the idea of a world without an apocalypse, Black Dogs of another type shambled disagreeably behind us, demons of a more literal persuasion returned to our thoughts.

More simply, though, more universally, this was a book that hit the right nerve. It told us stories no one else thought to, it pinned together the country in which we lived in a new way. Forty-two years later it is a kind of totem, a touchstone. Speak of it and you will get a reaction “My god, we had that!” Copies zip and fly around eBay and Abebooks. It is common currency, it is a foundation on which many have built. Not bad for Reader’s Digest.

All extracts obviously ©Reader’s Digest and I hope they don’t mind my using them here.