The basic idea first occurred to Jackson after reading a wonderful article by Katherine Whitehorn in the Guardian about how drastically her life changed following the death of her husband. When he read the piece he happened to be staying in a cottage in one of the villages on the north Norfolk coast in mid-winter and the combination of character (namely, a recently-widowed woman) and location (bleakly beautiful, with the salt marshes stretching out towards the sea) seemed to fit together perfectly.
He liked the idea of writing about a woman who was in her sixties or seventies. Hadn’t considered working with a character like that before. It was a couple of years later before he did anything more about it. And it was probably only after he came up with a couple of minor twists to the narrative – one which is best avoided here in case you haven’t read the book yet … the other being that she is unwittingly on a sort of pilgrimage – that the novel started to take on a life of its own.