The novelist follows in the footsteps of the heroine of her new book, A Single Thread, on a pilgrimage between the two magnificent cathedrals of Winchester and Salisbury

When researching my novels I often do what my characters do. While writing Girl with a Pearl Earring, I took a painting class. For Remarkable Creatures, I hunted for fossils on the beach at Lyme Regis, just as Mary Anning did. For my latest novel, A Single Thread, I learned needlepoint the way my heroine Violet Speedwell does – to make cushions and kneelers for Winchester cathedral in the 1930s.

That wasn’t the only on-the-job training I did. I also literally followed in Violet’s footsteps as she walked cross-country between Winchester and Salisbury cathedrals in her summer holidays. Who could resist walking between two of the UK’s finest cathedrals? It would be a modern-day pilgrimage across some of southern England’s finest green and pleasant land, and there is even a well-marked path to follow called the Clarendon Way.

In an ideal world I would do such a walk just as I am writing the scenes. In May 2018 my husband Jon and I set aside a weekend, but cancelled when I caught a cold. A few weekends later I thought I would try again, though Jon wasn’t free. But I hesitated. For something happens during Violet’s walk: a man begins following her in a cornfield and she runs. Almost 90 years later, much has changed for the better for women. We have more access to higher education. All kinds of career paths are open to us. And unlike in Violet’s world, it is no longer assumed that we will marry and have children. But we still don’t feel safe walking alone.

I wrote the scenes anyway, finished the book and in October, while I was editing it, Jon and I at last found a free weekend.

Facebook Twitter Pinterest The author at Winchester Cathedral.

October weather can be very different from May sunshine. We started in cold mist in Winchester, the cathedral rising romantically from the gloom. I wished I could stay inside it, admiring the longest nave in Europe, Jane Austen’s grave, and remarkable stone and wood carvings. But pilgrims don’t linger. As we walked up the High Street and through the medieval West Gate, it began to spit with rain, which carried on as we crossed the railway line and passed the prison and hospital, just as Violet does on a hot August morning.

It rained harder as we walked through the suburbs – houses Violet would not have seen. I know because I was carrying a 1930s Ordnance Survey map to consult alongside our modern one. I looked for an orchard that is marked on the old map, hoping to spy a gnarled old apple tree, but there were only 1960s bungalows.

As we finally left the city and joined the Clarendon Way, it really began to pour. “I’m sure this is beautiful in the sunshine,” I kept saying as the rain tested my raincoat’s mettle. By then we’d also donned the ultimate humiliation – waterproof trousers, which swished as we walked and made me feel about four years old.

We’d planned a break at Farley Mount, an 18th-century folly erected by a local man in honour of his racehorse, which he had saddled with the bizarre name Beware Chalk Pit. Violet has the same idea. Oddly, in this instance, life mirrored art. In my scene, Violet is planning to eat her breakfast rolls at the monument while admiring the view. But a visiting family is there already: the wife gives her the side-eye for being a woman on her own, and Violet feels forced to move on.

Facebook Twitter Pinterest The author at Farley Mount pyramid. Photograph: Handout

We were planning to sit inside the white pyramid to rest and dry off. But two dog walkers had the same idea and their frisky hounds enjoyed barking inside the echoey chamber so much we had to flee the noise.

In rain or shine, the Clarendon Way is a heavenly walk, along straight Roman roads and up and down hills, offering views of green and brown fields broken up by hedgerows and clumps of woods.

Finding the cornfield where Violet meets the lone man, I was now struck by how very different life and art can be. Where there had been corn there were just benign turnips. “But this is where the fear began!” I thought. Maybe we would have better luck at the John O’Gaunt Inn in tiny Horsebridge, which Violet flees to. But here again, life did not imitate art: I popped in to look around, and the whole geography of the interior was completely unlike what I’d imagined: the bar was in a different place, and it was bright and airy rather than dingy and smelling of chip fat. Plus the staff were friendly, whereas I made the 1930s publican nosy and sinister.

Facebook Twitter Pinterest The John O’Gaunt Inn in Horsebridge offered a friendly welcome

As we trudged past the many tributaries of the chalky River Test, where modern dry fly fishing was born, anglers unbothered by the rain plied their lines. Then came Broughton, where later that night we had an excellent, unexpectedly creative meal at The Tally Ho! inn. From there we momentarily diverged from the Clarendon Way and strode across country to our B&B in Nether Wallop where, after 15 miles in the rain, I hung my sopping clothes over the radiators and did what Violet does: “She kicked off her boots and was asleep in a minute.”

In the morning, sunshine transformed everything. Nether Wallop may have a joke name, but it is a lovely village, with thick thatch hanging over windows like eyebrows and actual roses around the doors. Used for filming the Miss Marple BBC TV series, it is also where Violet’s love interest Arthur lives and rings bells. Here we met friends who were joining us for the second 13 miles of the route .

Facebook Twitter Pinterest Clarendon Palace ruins, near Salisbury. Photograph: Richard Newton/Alamy

Twenty-six miles has a certain ring to it. Add 0.2 miles and you get … a marathon. Which is what we found running towards us along the narrow path – 1,000 participants in the annual Clarendon Way marathon. Rather than swim against this wall of humanity, we cheated and went around, cutting seven miles off the distance. We finished the route in mellow autumn sunshine with the leaves just beginning to turn, walking through sleepy villages and past harvested fields.

Just outside Salisbury we passed through Clarendon Park, an old hunting ground, and the ruins of Clarendon Palace, built by Henry II in the 12th century. Now it is all crumbling flint walls, surreally populated with grazing llamas.

Poor Salisbury has been in the news for all the wrong reasons, but it appeared to have bullishly recovered from Russian interference. Its cathedral is a corker, with its 123-metre spire dominating the skyline. It has beautiful stained glass, especially the gorgeous modern “Prisoners of Conscience” window in the eastern end. The Chapter House famously houses a copy of the Magna Carta. I touched the walls of the cathedral, bringing greetings from that other great cathedral I had just walked from, my pilgrimage complete. Despite the rain, I was glad I’d done it, and would do it again – the whole thing next time. I just need to check when the marathon is.

• A Single Thread is published by Borough (£14.99). To order a copy for £11.99 go to guardianbookshop.com. Free UK p&p on online orders over £15