Kate Riordan sets the scene for The Girl in the Photograph

Writers disagree about what should come first in the creation of a book – plot or characters. Traditionally, though the line has always been blurred by some, it's assumed that commercial fiction is plotty, whereas literary fiction is more interested in people. I'm not sure, then, where that leaves me, because my starting point for The Girl in the Photograph was neither. I began with the setting.

All my favourite books have memorable settings. I like my characters to inhabit a world I can step into and lose myself: a tangible, seductive place that calls to me whenever I put the book down. I feel happiest in old houses and in the countryside and so most of my favourite settings combine the two, from the fields and hamlets of Hardy's Tess of the d’Urbervilles to the grand house and kitchen gardens of L. P. Hartley's The Go-Between.

I love films nearly as much as I love books and much of that is to do with setting, too. While some readers like the writer to hold back, so they can do most of the imagining themselves, I like cinematographic stories which introduce you to their fictional world with a great big sweeping panning shot. It doesn’t have to be idyllic and pastoral, either: the 'raw afternoon' in London that opens Dickens’ Bleak House is surely one of literature’s best examples of 'how to set the scene'.

But a good setting is always more than a mere backcloth, however vividly drawn. It can be an unforgettable character in its own right and it can direct the plot, too. In my story, Fiercombe Manor and the valley it nestles in stand for the past and times lost. I wanted the place to be as melancholy as it was beautiful, and as powerful in influencing my main character Alice's moods and feelings as any other plot twist or person in the story.

Though I changed elements of it, and all the events that happen there are completely fictitious, Fiercombe is based on a real location in Gloucestershire. Owlpen Manor, set deep in a thickly – wooded valley, is a wonderful place: full of atmosphere, history and even a few ghosts. I first visited it a few years ago, when I was writing a travel piece for Time Out, and fell in love with it immediately. It feels enchanted, secret and timeless; Vita Sackville-West summed it up when she wrote, 'Owlpen in Gloucestershire … ah, what a dream is there!' I'd only been there a few hours when I thought to myself, 'Now this is a place I have to set a novel'.

Renamed Fiercombe Manor in my book, it emerged well before anything else and remained unchanged through rewrites and edits. Without any sort of plan or plot, the first scene I sat down and wrote was Alice’s arrival in the silent valley: down, down to the ancient manor, weaving through the beech trees; a stranger in a strange but beautiful place. I didn't yet know why she was there or what would happen to her, but I knew the place would mark her, and that she would never be the same again.