FOR A CHANGE, A SUNNY DAY. AT St Paul’s I cross the river, turn at Tate Modern and continue east, past the Globe, past Southwark Cathedral, until I reach Tower Bridge and cross back, making my way to my desk in Wapping. It’s a shorter walk if you keep on the northern side of the river, but not nearly so pleasant, not on a morning like this.

There’s my map; but in this week’s Books you’ll find another, a map of William Blake’s London, provided for us by his biographer, Peter Ackroyd. Ackroyd is, of course, not only the biographer of Blake but of London itself, and later this year he takes on the Thames. A few years ago, when Peter’s biography of Thomas More was published, I followed him on a walk through More’s London. When More was born, in the 15th century, Fleet Street was a flowing river; when he died, another 100 years would pass before the birth of Sir Christopher Wren. London would have been an utterly different place, unrecognis-able, surely, to a modern Londoner. And yet, in Ackroyd’s company, More’s London was perfectly vivid, and not just because Ackroyd made it so. “I walked the old perimeter of the London wall the other day,” he told me. A few shards of the wall, Roman and medieval, are still scattered about the City. “I noticed that the wall is now covered with security cameras – so it’s retained its defensive purpose.” By Ludgate Circus we saw a young man in the striped jacket of the floor of the London Stock Exchange; it recalled the parti-coloured barrister’s gown More would have worn at the Bar.

So it is with Blake’s London in the 250th year since that visionary poet was born; but so it is too with many writers, many landscapes. One of my greatest pleasures, as a reader, has been looking up from the pages of a book to see the landscape that inspired it. It may be a book of history, and I may find myself on the battlefield at Agincourt or Antietam; it may be a book of poetry, and I’ll head to Ted Hughes’s Yorkshire or Alice Oswald’s Devon. There is Alan Garner’s Cheshire and Carl Hiaasen’s Florida, Walt Whitman’s New York. Nothing is ever placeless.

I’m not saying that you have to travel to enjoy books, whether books about battles or books of poems. But there are times when, if you’re like me, you simply have to get out of the house, and you might as well follow the directions you get from a book.

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