I wake to the sound of poet Michael Horovitz singing a William Blake poem on Radio 4’s Today programme. On the Tube I sit across from a Poems on the Underground poster of Blake’s Infant Joy. In the courtyard outside the British Library I pass Eduardo Paolozzi’s statue of Newton hunched over his compass, the design based on Blake’s painting. Walking down my street, I hear a neighbour’s radio tuned to the cricket; Blake’s Jerusalem wafts through the window.

What is it with William Blake? He seems to have penetrated British life in a way few other poets or artists have managed. When I mention I’ve written a novel about Blake, British people never look blank. Instead, more often than not, they begin reciting “Tyger tyger, burning bright,” or “To see a world in a grain of sand.” Or they say, “He used to sit naked in his garden, didn’t he?”

Being American, I barely knew of Blake when I first arrived in the UK in my late teens. He is rarely taught in school in the US; my father had to go to the library to look him up when I said Blake was the subject of my novel. I had read his Songs of Innocence and of Experience as a student, but only began to take in his significance as a British artist and icon when I first saw his paintings and coloured prints on display at the Tate – dark, glittering jewels representing Newton, Nebuchadnezzar, God judging Adam, and a hideous scaly man with his tongue sticking out that Blake called The Ghost of a Flea. (When I recently showed that image to a bunch of schoolchildren and told them the title, they roared with laughter.) The images were intense and terrifying, and I couldn’t take my eyes off them.

Many years after my initiation into Blake, in late 2000, the Tate opened an exhibition on him, pulling together the many strands of his work, his vision, and his life. Seeing it all in one place overwhelmed me. I remember standing in one of the rooms and thinking, “This guy was crazy, or on drugs, or both. I have to write about him!” It seemed to me that he would be considered just as radical and incomprehensible if he lived today as he had been in his own time. And yet, we are all still drawn to him like Eve to the apple. I wanted to understand why.

Why do so many artists cite Blake as a major influence? Why are people happy to belt out Jerusalem at English weddings when the meaning is obscure? Why do his works cause bun fights and sell for millions, at the rare moments when they resurface – as did a set of his long-lost watercolours in a Glasgow bookshop six years ago?

It’s not immediately obvious that Blake would be so appealing, as, say, Keats, Manet, Vermeer. His writings, apart from Songs of Innocence and of Experience, are dense and set out a personal philosophical system that is incomprehensible to all but the most dedicated scholars. His art, while original and beautifully rendered, illustrates theological concerns alien to this secular age.

Having spent three years with Blake and those who love him, I have a theory or two about his popularity. For one thing, he appeals to a wide variety of people because his range of interests was itself so wide. Art, literature, religion, philosophy, politics: Blake had significant things to say about all of these major subjects.

I think he is also appreciated for how he chose to live his life as much as for his work. Blake was undervalued in his time; he lived hand-to-mouth for much of his life. By the time he died, he and his wife Catherine were reduced to living in two rooms off the Strand, getting by on small commissions ordered by pitying friends. He had little head for business, and no willingness to compromise his style.

Many, especially creative types, can relate to Blake’s misfortune, as well as take comfort from the growth of his posthumous reputation. If you are an artist and no one is buying your paintings, it’s nice to know that someone of the stature of Blake went through the same experience. Moreover, in this day of websites and blogs, Blake’s decision to print his own books doesn’t seem unusual at all.

Blake’s determination to go his own way – seeing angels in trees, visited daily by his dead brother Robert, working out a philosophy no one could understand – made him the quintessential English eccentric. The British love such quirky behaviour. Even if they don’t understand what he was getting at in Jerusalem, they cheer on a man who, with his wife, was supposedly discovered naked in his garden, reading Paradise Lost aloud. “Come in,” he is meant to have said to his friend Thomas Butts, “it’s only Adam and Eve, you know!”

I’m a sucker for an English eccentric as much as any Brit, and during my research I found, in my increasingly frustrated search for a comprehensible William Blake, that I kept circling back to that image of him and Catherine nude in their garden. Scholars have dismissed the story as apocryphal, but I like it because it humanises him, makes him a little foolish and a little loveable. It occurred to me that writing about Blake from this point of view – from the neighbours’ gardens and the nearby streets – would perhaps bring Blake closer to us. If we can imagine living next door to him, we might be able also to imagine having a sensible conversation with him – about the weather, about his work, about the French Revolution.

I always visit the places where I set my books. I know other writers have successfully recreated landscapes from their armchairs, but that seems such hard work to me. I’d rather walk around and record what I see left of the past. Getting down and dirty in Lambeth, however, turned out to be less than helpful. The area was a victim of the industrial revolution in Blake’s time, with factories and warehouses rapidly springing up along the Thames. It is even worse now. What the railway didn’t cut through when Waterloo Station was built in 1848, the Second World War finished off with bombs. The area is a hodgepodge of modern blocks, and trains rumbling overhead. There is virtually nothing left of the 18th century in Lambeth’s streets. Only a spattering of buildings – Lambeth Palace, a row of houses along Walnut Tree Walk, a green in St Mary’s Gardens – remind us of its past.

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