Caitlin Davies has laid ghosts to rest in her books before.
In Place of Reeds (2005) she recounted with unflinching dignity the true story of a brutal assault that she suffered while living in Botswana. On a bright spring day sitting outside a pub near her home in north London, the subject is not one she is especially keen to resurrect. "I have written about it now," she says emphatically, "and I want to be able to show my daughter this piece, erm, and she knows a bit but, er ...." We let the subject float there. Anyway, it's ghosts of a fictional nature we're here to discuss.
Since writing Place of Reeds, Davies has completed two works of fiction and now her third novel, The Ghost of Lily Painter, which deserves to propel her firmly into the Richard and Judy league. But although she is the daughter of the novelist Margaret Forster and the journalist Hunter Davies, Caitlin is more used to propping up her own writing career with teaching than she is receiving praise from a total stranger. "Do you really like it?" she asks more than once. "Because I've had 20 odd years of writing and rejection and all I want to do is earn a living. When your first book is published you think, 'This is it, I've finally sold a book,' but then the next one gets rejected. And the next one ...."
Has it been daunting, her parents being who they are? "No, because you get the luxury of seeing your parents do what they love to do and how many people can say that? Obviously, you go through the groans, and dad always seemed to be looking at a newspaper in the morning complaining that they'd cut all his jokes out."
Set not a million miles from where we are sitting (Davies moved here in 2007), The Ghost of Lily Painter flits back and forth through about 100 years in the life of an Edwardian terraced house. Reluctantly, Davies admits that there are similarities between herself and the novel's 21st-century protagonist, Annie Sweet. "I suppose there are," she says. "I moved into a house and started thinking, 'I wonder who used to live here?' I got a bit obsessed by it in any free time I had. And now I've written a book about a woman doing exactly that. But we're not the same people and she has a lot more success than I did in real life. I kept coming to dead ends, but then the reason I liked doing this book is that it's all made up."
Not all of it, I point out. Because in the course of trying to find out more about the people who had lived in her own house, Davies uncovered a dark and little-known episode in the history of her area. "It started because I wanted to know how average Edwardians lived. You can find out about lords and ladies and kings and queens, and you can read about slums and tenements, but I wanted to know how, say, a police inspector would have lived at around the time of the 1901 census." That particular line of inquiry led Davies to delve deeper into the history of Holloway Prison, a local landmark.
"I was Googling, and the entry for the prison listed all the people who had been executed there. It said that the first women to have been hanged at Holloway were the two baby farmers Amelia Sach and Annie Walters. My first thought was, 'What on earth was a baby farmer?' And then you're off: you've got the history of the house, the picture I'd been building up of Edwardian times, and then this crime that happened in exactly that period. And I was living right in the middle of that story."
It is almost impossible to comprehend now, but baby farming – charging young, pregnant women to stay at "lying-in" residences where they could give birth and then walk away, no questions asked, while their babies were given up for adoption – was a common and legal practice in the early 1900s. Sach and Walters differed from the norm only in that the newborns left behind at Sach's house in East Finchley were handed over to Walters and murdered.
No one knows how many babies met this fate and no one is sure that Sach knew of the killings. What is certain is that on 3 February 1903, Sach and Walters were executed together: the only double hanging of women in modern British history.
As the strands of the story took shape in Davies's head, she set about exploring the area of London she had moved to after her 12 years in Botswana. "Although I grew up around Camden, I never knew Holloway at all. I remember going to the cinema, but that was it. Now, I'd much rather walk around here than, say, Hampstead. If I go there I feel despair and intimidation looking in shop windows. Give me the Holloway Road and Seven Sisters any day."
And so it is here that Davies finally seems to have found the safety of home. And while it would be tempting to say something along the lines of "the pains of the past are etched on her face", the truth is that there is not much to distinguish Davies from any of the other mothers she would see outside the school gates.
Her daughter Ruby, now 11, is the result of her marriage to Ron, who remains in Botswana. Now divorced, Davies has since settled down with a "press photographer" who walks the dog and helps look after Ruby. It is a scenario typical of the area around us and yet there are still plenty of ghosts left for Davies to lay to rest.
Her next novel, she says, will be about another subject that haunts her: unwanted mixed-race babies abandoned once African-American GIs left the UK after the Second World War.
So does Davies believe in ghosts? "I do, actually," she says. "Funny, isn't it? But the ghosts I've come into contact with are not scary. I saw one in Botswana and my ex-husband's grandmother told me I should have just asked it what it wanted. Ruby's sort of worried about ghosts and kids can freak themselves out. So I tell her: 'Don't worry, I've seen a ghost. It's fine'."
The Ghost of Lily Painter, By Caitlin Davies (Hutchinson, £12.99)
"She goes up the stairs and the carpeted boards creak beneath her feet. She stops at Molly's bedroom and listens to her daughter breathing. She does not realise the child is awake again; instead she watches her and smiles because she loves her so. And as she turns to go to the bedroom I am watching her and I think, No, you will not sleep, you will not feel comfortable in this house, not until you have found out what happened to my child."