Few would deny that Highgate Cemetery is the most atmospheric, romantic enclave in London — the natural setting, surely, for a thrilling narrative. The American novelist Tracy Chevalier first espied its Gothic tombs and catacombs ten years ago and decided: “I’ve got to set a novel here.” So, after mesmerising readers with Girl With a Pearl Earring, inspired by Vermeer’s painting, she initiated us into another strange world with her Falling Angels, set in this Victorian Valhalla (as Betjeman called the cemetery) just after the death of Queen Victoria.

This was the moment when Highgate Cemetery’s fortunes began to change, and a hugely successful business began its slow decline. By 1975 it was bankrupt, vandalised and derelict. Its survival and preservation has been thanks to the dedicated volunteers from the charity Friends of Highgate Cemetery, who took control 30 years ago.

Before embarking on her novel, determined to get to know the place thoroughly, Chevalier volunteered with the Friends first as a gardener, helping to tame the wilderness that is Highgate’s keynote, and then became a tour guide. You may still find her there some days. I joined her one morning to a backdrop of birdsong and church bells. Visitors can’t just wander at will among those tumbled gravestones. “Not even the Queen may go round unaccompanied,” says Jean Pateman, chairman of the Friends. It is, after all, still a working burial ground; you have to phone in advance and book to join a tour.

Chevalier is an ideal companion. Doing these tours has been a learning curve. She’s accustomed now to the ghoulish Goths and the most frequently asked question — Have you seen any ghosts? “On my first tour here, I hadn’t yet figured out what the public wanted, which is stories. It made me more confident about speaking in public.”

We paused at the grave of James Selby, coachdriver on the Brighton run, who died at 45 in 1888. The symbols on his gravestone — the horn and whip of his profession, and an upside-down horseshoe — introduce us to the cemetery’s recurring symbols of death: a burning torch upside down (the flame of eternal life); the broken column (a body cut off in its prime); a weeping woman clutching an evergreen wreath (eternal life/youth); an empty chair, as if the occupant has suddenly been called away; and, of course the ubiquitous angels to carry you up to Heaven. “You learn to read a Victorian tomb,” Chevalier says, “and of course, for the Victorians, the tomb was an extension of their home: the more words engraved and symbols carved, the greater the expenditure.”

Highgate Cemetery opened in 1839, when the average age of its corpses was 36. Chevalier, who researches intensely for each book, immersed herself in Victorian mourning and funerary lore. She intended to write a book set in the cemetery in the present “but I realised that it’s the layers of history underneath all the vegetation that make it interesting” and dreamt up a tale of two families owning adjacent burial plots, with an undercurrent of class differences manifest in the sentimental angel and the more classical stone urn.

We learn that a Victorian widow mourned for two years in a dress of paramatta silk trimmed with crepe, with black gloves, and handkerchiefs edged in black. “The rigid Victorian rules were very comforting. And for so many people now there is no religion, and no rules. But people might see a Victorian funeral in a film like Oliver Twist and they say, ‘I want something like that’. And then we get a funeral with plumed black horses.”

As we marvel at the richness of overgrowth, the vast laurel tree at the gateway to the catacombs, she reminds me: “This is nothing like what it looked like originally. The cemetery owners employed 28 gardeners who cultivated the place as a grassy hillside, covered in monuments, with a few ornamental evergreens. The idea that it should become a neo-Gothic, romantic place overgrown with ivy was never thought of.”

The volunteers fell invasive trees and plant oaks, birches and wild flowers. “We dig out ground elder, yank ivy off monuments, keep paths free of weeds, clear the views — so here you can see the pyramid, built in memory of a small boy. I love uncovering graves. I think the dead don’t mind being uncovered.”

One of her fellow gardeners was the late John Gay, the great photographer whose images — stone angels, sad-eyed dog — are so familiar from postcards. The dog lies on the tomb of Thomas Sayers, the bare-fisted boxer. “When he died, he was as famous as Muhammad Ali,” Chevalier tells me. “He would drive about in his phaeton with his dog, Lion, on the passenger seat. When he died 100,000 people lined his funeral route down Tottenham Court Road. ”

One day Chevalier was weeding the undergrowth when she was introduced to another tour guide, and was astonished to discover, as they talked, that this was none other than Audrey Niffenegger, author of the hugely successful novel The Time Traveler’s Wife. So there are two American novelists enthralled by Highgate Cemetery. Niffenegger lives and teaches in Chicago, but guides tours whenever she’s in London. Chicago’s cemetery, she told me, is called Graceland and is, like most American cemeteries, orderly, flat and trimly mown. She first encountered Highgate when studying the Rossetti family.

Now she too is writing a novel set near by. “What I love about Highgate,” Niffenegger says, “is that it’s a muddled microcosm of society, with illustrious Victorians and more recent dead, cheek by jowl.” Because she is partial to circuses and sideshows, we went to visit Nero the lion in his somnolent posture on the tomb of George Wombwell, who ran England’s first travelling menagerie.

Near by is the tomb of Mrs Henry Wood, the novelist, who Chevalier tells me did NOT write the line “Dead, and never called me mother”. We take in the Columbarium, with the shelves of coffins, the 300-year-old cedar of Lebanon, the huge vault of Julius Beer, who founded The Observer, the monuments to Rowland Hill of postage fame and Faraday the scientist. Karl Marx in the East cemetery attracts most pilgrims; others visit Mary Ann Evans (George Eliot) and Radclyffe Hall in the vault of her friend Mabel Batten. The guidebook’s list of those buried here is simple and egalitarian. Foot, P, journalist (that’s Paul, a latter-day arrival) would enjoy being so close to Marx, K, philosopher and political writer. “Dickens John, Elizabeth and Catherine” — the parents and wife of Charles, who lies in Westminster Abbey — are on the wild side.

More tourists than native Londoners find their way here. It is not easy to get to (it’s nowhere near Highgate Tube station, a walk from the nearest bus route, and there’s no adjacent parking) and its steep wooded paths are not for the infirm, or for small children. Still, the cemetery is in need of more volunteer guides and understaffed. They can’t depend on a constant supply of American novelists discovering its charms.

March-November, daily tour, 2pm; winter, weekend tours on the hour 11am-3pm. Entrance, £5. Details: 020-8340 1834

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