The setting of a story is vital for a historical novelist, perhaps even more than for those whose books are set in the present. This is for the blindingly obvious reason that a contemporary novel is set in a place or a milieu, whereas a historical novel has not only a place but a time. In other words, the setting has two components, rather than one.

When I’m writing one of my historical crime novels, I almost always start with the setting, in this double sense of the word. My latest novel, A Schooling in Murder, began with a real place. It’s called Piercefield. Transformed to my fictional variant, it has become Monkshill Park.

Three hundred years ago Piercefield consisted of a Welsh mansion surrounded by a substantial park to the north of Chepstow. It’s bounded to the east by a precipitous descent to a loop of the River Wye. Beyond the river lies England.

During the eighteenth century, the grounds were extensively landscaped. Walks were laid out, linking a series of viewpoints and eyecatchers both in the park and overlooking the Wye. Piercefield became a tourist attraction. Later in the eighteenth century, the Tudor mansion was substantially rebuilt according to designs principally attributed to the collector and architect Sir John Soane. A Jane Austen heroine would have found the result most agreeable. She might even have wanted to the proprietor.

For all its ambition and elegance, however, Piercefield was an unlucky place. During the eighteenth and nineteenth centuries it changed hands frequently, usually because its owners could no longer afford to keep it up. One of them was Nathaniel Wells, a former slave who inherited his father’s plantations in the Caribbean and settled down as a landed gentleman in Monmouthshire; he became a Justice of the Peace and High Sheriff of the county before the sugar money ran low and he had to sell.

In the twentieth century, the estate went into a steep decline. After World War II, the house’s fittings were sold off, many of them to museums, and the shell left to decay. Nowadays the park is reduced in size, and Chepstow Racecourse occupies most of its western portion. The house itself is a roofless box of cracked stone and crumbling brick surrounded by a security fence. But there are still footpaths, and you can still visit the outside of the mansion and walk along the heavily wooded ridge above the river and find traces of those eighteenth-century viewpoints.

I have been visiting Piercefield for thirty years. At first it was possible to enter the ruined interior of the house and explore what remained of the extensive kitchen garden and the stables. That can no longer be done. Every year, the decay advances a little further. In another twenty years, despite herculean efforts by local people, all that may be left of the house is a pile of rubble buried in weeds and scrub.

If you want to find out more about Piercefield’s history, I would recommend as a starting point Early Tourists in Wales (search for Piercefield), a useful illustrated resource with many suggestions for further research.

I created Monkshill Park, the fictional cousin of Piercefield, over twenty years ago for a novel called The American Boy (2003) about the English boyhood of Edgar Allan Poe. This was set in 1819-20 and showed Monkshill in its splendid prime. But, as the real Piercefield continued its inexorable decline, I felt an increasing desire to go back to my fictional Monkshill and discover what had happened to it more than a century after the events in The American Boy.

Hence A Schooling in Murder, which is set in 1945 between VE Day and VJ Day. The local farmer has taken over most of the park in the name of the war effort. The house itself is in poor repair. It was briefly occupied by the army and is currently the home of a third-rate boarding school for girls. One of the teachers has disappeared…

Whatever happens to Piercefield, it will still exist in the memory and flourish in the imagination. One day, I suspect, I shall return to Monkshill Park at another moment in its history and see what time has done to the place at another point in its long decline. As ever, the setting will come first. The time and the place.

Andrew Taylor is a bestselling novelist and author of A Schooling in Murder.