It is interesting to speculate, as I walk towards the walls of the Globe Theatre in Southwark to meet Peter Ackroyd, on the connection between biographer and subject. It is a very English day; a Sunday, bright, blowy and violently rainy in turns, the green-grey Thames sliding along between St Paul’s and the South Bank, tourists and Londoners eating ice-creams and trying to keep their umbrellas from turning inside out, sometimes simultaneously. There he is, below the lime-white wall of the resurrected Globe: in his mid-fifties, to be sure, not his mid-forties, but we all live longer now than we did in the 16th and 17th centuries, and as I wave at him and call his name, I recall his description of Shakespeare in his creative prime. Perhaps you will see, in the photographs, the resemblance I think I see, though to my knowledge Mr Ackroyd has never had a beard, and his hair, what is left of it, is rather tawnier than auburn or chestnut. Certainly, however, his cranium evinces great susceptibility, activity, quickness and love of action.

In an age when we don’t have much truck with the notion of great men (or, indeed, women) of letters, it is worth suggesting that they might still exist — and that Peter Ackroyd could more than stake a claim to stand among them. Raised in an Acton council house by his mother — his father left home when he was a baby, and they have never met — he evinced prodigious talent from an early age. Educated at Cambridge and then at Yale, he was for some time a journalist — the youngest literary editor The Spectator, an achievement that somehow recalls that of a youthful, vigorous journalist called Charles Dickens.

Ackroyd’s vast biography of Dickens, published nearly 15 years ago, was one of the first to break the mould of “conventional” biography, including as it did conversations between author and subject. Readers and reviewers were startled; yet these days it’s clear — from books such as Edmund Morris’s biography of Ronald Reagan to Andrew Motion’s Wainewright the Poisoner — that he was simply ahead of his time.

Like William Blake, whose life he chronicled less than a decade later, you could call him something of a visionary, though his modesty wouldn’t allow him to make such claims himself. Early on in our acquaintance — I have known him for ten years, while I have been literary editor (not so young any more) of The Times, and he has been writing for our books pages — I praised his remarkable and mysterious novel, Hawksmoor, which won the Whitbread and Guardian fiction prizes when it was published in 1985. We were in a restaurant; he looked away from me, and down at his lunch. “A trifle,” he said. “My dear. A trifle.”

I don’t think it’s false modesty. When we sit, now, talking about Shakespeare in a café near the Globe, he won’t look me in the eye when talking about himself; his glance slides away, as if some escape is offered this way. I thank him for agreeing to an interview; I know you don’t like them, I say. “I hate it,” he says, and yet he is diligent, energetic and engaged with the job at hand, as great a believer in the power of hard work as Shakespeare himself.

It seems to me inevitable that he should finally have chronicled the life of — could we say, the greatest Englishman? Ackroyd, with his lives of Eliot, Blake, Thomas More, Dickens, his novels imbued with English history and landscape, his magisterial and unique biography of London and, most recently, Albion, his examination of the what he calls the “English imagination”, could hardly have avoided finally coming to grips with William Shakespeare. He agrees. “It was an inevitable decision. Like a fatality — no, not in that sense.”

He knows he has the wrong word, yet it draws both of us, I think, up short; Ackroyd had a heart attack a few years ago, just as he was writing the final lines of London. It hardly slowed him down, it’s worth remarking; he filed reviews, as I recall, from the hospital. “Like fate, I mean. I had to do it. I suppose if you want to write biography in the first place, then his biography poses perhaps the greatest challenge of all.”

Why? Because, of course, there’s so little to say. What, precisely, is known about Shakespeare? He was born in 1564, perhaps on St George’s Day, April 23, but then perhaps not. He died in 1616, and in between those dates he wrote some three dozen plays, depending on how you reckon his authorship. He was the son of John Shakespeare, a glover of Stratfordupon-Avon; he was married and fathered children, including a son, Hamnet, who died young, but of his relationships with his family one can say almost nothing. There are no letters, and few scraps at all of his handwriting. There are legal documents, a few, and a will, and the biographer can attest that his work was done in the busy turmoil of the theatrical world that flourished in London — despite threats of plague and political upheaval — at the end of the 16th century. Lord Strange’s Men, The Lord Chamberlain’s Men, The King’s Men — among these fluid companies of actors, writers, managers, Shakespeare clearly thrived, but his work alone, rather than any real record of his life as it was lived from day to day, survives to bear witness.

I walk with Ackroyd the few steps in Southwark that take a visitor though what would have been Shakespeare’s haunts in his prime. The site of the old Globe, a hundred yards from where the present one stands; Rose Alley, where the remains of the old Rose Theatre lie buried beneath more modern buildings; someone has recently chalked the outline of a bear and a rose, oddly recent testimony to the life — bear-pits and all — that once teemed here.

It is graffiti that bears handy witness to Ackroyd’s notion that life and time, in London, are somehow ever-recurrent, circular. “Shakespeare,” he says, “is to a large extent invisible. With other writers there was always something — their beliefs, their myths, their sensibility — which you could investigate quite thoroughly. In the case of More it was his Catholicism; in the case of Blake it was his visionary mythology. By exploring just that one aspect it was possible to open their consciousness on other levels. But with Shakespeare, there’s no such thing. He seems to have no beliefs, no presumptions, no faith. So you are sort of barred from entering his consciousness in the most obvious way. You have to do it circuitously, which is actually quite a difficult feat.”

In a sense, Shakespeare must be absent from his own biography; somehow, Peter Ackroyd makes this deficit into a strength. He does this by echoing, with his own energy, the energy that must have been Shakespeare’s. He throws us into the life of London which he knows so well — the sights, the sounds, the smells, the dangers and the delights. He reads the plays and seeks, not for biographical explanation or psychological revelation, but for the mutable, devouring genius whose eye, apparently, could see anything from any point of view. Yet this mercurial elusiveness seems somehow personal in Ackroyd’s book; for Ackroyd too has always seemed to me a human being made not of conviction, or of belief — except the belief in the power of sheer endeavour.

For a biographer, Ackroyd is oddly uninterested in the personal: and yet, to my mind, that makes him a fine biographer, for his focus is always on the work. The work is the record; the work shows the truth of the life. It is as true of his own life, too. We can know the facts — that he has lived alone since his lover, Brian Kuhn, died more than ten years ago, that he is not averse to a drink or two — but they do not seem of any concern to Ackroyd.

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