My three-year-old daughter, Rosalyn, is happily chatting away as we walk through countryside near our home. She is telling me about her morning at pre-school, the games she played and how she wants pasta for dinner, flitting from one subject to another in her usual excitable babble.
"I've got a new best friend," she announces. "How lovely," I say. "What's her name?"
"Tilly. She lives in our house," comes the reply. "She's my friend, and she's dead. Alex is my friend, too. He lives here. He died. His mummy and grandad died, too. We play babies together," she announces, before moving on to the merits of strawberry ice cream over chocolate.
There is something about the matter-of-fact way she tells me this, with that earnest naivety of a toddler, that makes my blood run cold.
We don't know anyone called Tilly or Alex, nor have I ever talked to Rosalyn about death or the afterlife. The most she knows about this subject is when her grandparents' cat was put to sleep, so I have no idea where this is coming from.
I've always prided myself on being an entirely rational, practical and sensible woman. A journalist for the past 17 years, I like facts and evidence. I am not superstitious, nor do I believe in ghosts.
Which is just as well. My husband Adrian, 40, works away in London during the week, so it is largely just myself and Rosalyn in our North Devon house, which dates back to the 1500s.
Our nearest neighbours are half a mile away and we live in the middle of a wood. I simply cannot allow myself to be scared by — let alone believe in — the supernatural.
But this isn't the first time Rosalyn has spooked me. When she was 18 months old, I remember how she pointed to an outside cellar door and was adamant she could see sheep. I dismissed it at the time, but she kept shouting: "Look, Mummy, sheep, sheep!" A few weeks later, we walked past again and she announced with a sad face: "Sheep gone now, Mummy."
Although aware our house is built on the site of old sheep farming cottages, I put it to the back of my mind. After all, Rosalyn was just grappling with the rudiments of speech; she could have meant anything.
But now she's three, and much more articulate and focused. And she continues to tell me about Tilly and Alex. No wonder I have started to feel unsettled in our home of three years. Although I don't believe in ghosts, I would be lying if I said the idea of them didn't scare me. There is so much in life we don't understand, so much we don't know, and there are so many accounts of people saying they've seen things they cannot rationally explain.
I decided to do some digging, in an effort to convince myself that there is nothing to Rosalyn's imaginings.
I wish I hadn't.
Census records for 1861 show there was a ten-year-old boy called Alexander Turner living here. And records for 30 years later, in 1891, list a Matilda Oke, aged 20. Records are patchy from this time, so it's very likely that Matilda was living here when she was much younger.
Although I am struggling to convince myself that Alex, Tilly and the visiting flock of sheep are nothing more than the creation of a toddler's vivid imagination, a recent study reveals that one in five Britons claims to have experienced the presence of a ghost.
I did some research and discovered that there are many rational parents in the same position as me — with children like the little boy, played by Haley Joel Osment, in the film The Sixth Sense — who say they 'see dead people'.
Take mother-of-six Katie Jones, 33, a carer from Canterbury, Kent. She has an 11-year-old daughter Alice, who, from the age of two, has spoken of seeing people who are no longer here. Katie, who is married to landlord Gareth, 47, explains: "When Alice was two, she started to cry a lot, saying there were two men in her room staring and shouting at her, and she didn't like it.
"She then started to say that a girl called Sheila sat at the bottom of her bed crying for her mummy. I looked in old newspaper cuttings and found that there was a girl of that name murdered here. It chilled me to the core.
"Alice then told me that my grandmother, also named Alice, who died a year before my daughter was born, was coming into her bedroom. She said that Nanna had told the girl and the men to go away, and they had."
Katie says Alice would accurately describe the clothes her grandmother wore, something she couldn't have known.
"When Alice was three, a family member had a stillborn baby. Alice told me that Nanna had been to see her with a baby in her arms. She said the baby was named Max. There is no way she could've known this. We hadn't told her about the baby or his name — she was too little to understand.
"As the years have passed, she still says Max and Nanna are there. She even told me it was Max's fourth birthday and, when I checked, she was right. She had the correct day and age."
Katie continues: 'When she was four, I remember her telling me that she had to give our next-door neighbour a message. Her husband had just died of cancer and she wanted to tell her to stop crying as he had told her he was fine.
"When she first started saying things, I brushed it off as the chatter of a little girl, but the more it happened the more I came to realise she was telling the truth. Now I have no doubt she has a gift.
"She has always felt comforted by her Nanna, but there have been some bad experiences. In our old house, she kept saying she saw a boy and she'd refuse to go upstairs. She'd stand there screaming, saying the boy wouldn't let her go past. It used to really scare me."
Now aged 11, Alice says that she's seeing things less and less, but can clearly remember seeing her great-grandmother. "I always felt safe with my Nanna there, and I remember seeing the baby, too. I also remember it being his birthday.
"I only feel scared when it's someone I don't know, but I see them less now. To any other children who see things like this, I would say you don't have to be scared, as they are just looking out for you and trying to protect you."
Dr Stephen Westgarth, a member of the Royal College of Psychiatrists, a consultant child psychiatrist and medical director of Child Psychiatry UK, says such behaviour is normal for a young child.
"Children's imaginative worlds are limitless, and don't contain the same social and physical rules of the adult world.
"As a parent, I wouldn't be worried about a child experiencing these episodes and, in some ways, it can be viewed as very positive, because it shows that they have a vivid and well-defined imagination.
'The normal situation would be that, as the child grows and the brain develops, they begin to rationalise what they are experiencing and so the episodes will begin to wane."
He says he has dealt with families who say their children are talking to "the beyond", but says these tended to be spiritualists and strong believers in the afterlife, so there was a culture there already.
Yet, like me, mother-of-two Tricia Jordan is not clairvoyant, but she is in no doubt that her son talks to the dead.
The 32-year-old medical secretary says her seven-year-old son, Luca, has been "seeing" her dead grandmother since he was a baby, which used to scare her, but she now feels comforted by it.
Tricia, from Newport, Gwent, who is married to postman Stuart, 37, and also has a four-year-old son, Bobby, says: 'My grandmother passed away when Luca was 18 months old. He had just started to speak, and the first thing he told me was how Granny would tuck him up in bed. I found it really strange. It used to scare me, and I'd change the subject.
'One of the eeriest things was him singing The Big Ship Sails On The Ally-Ally-O, which she always sang to me. He would sing it over and over, and tell me how Granny was there. I had never sung it to him. There is no way he could have known this song.
"As time went on, I realised he wasn't scared so it was all right."
She describes another encounter when he was four: "One day, we passed a house near our home. He told me it was Martin's house but he wasn't there because he died in a fire. I checked the names on a census and a Martin had lived there. This really scared me."
Luca hasn't had any spooky sightings for some years, and today he has no memory of seeing his dead grandmother.
Tricia says that, while she has always believed in an afterlife, what she has experienced with her son has left her utterly convinced that the dead walk among us.
She says: "I have always believed a little bit, but what I have seen with Luca blew my mind. It made me believe completely."
Hollie Smith from New Addington, South London, also shares this conviction. She is certain her six-year-old son, Riley, has seen ghosts. The 32-year-old, who runs a party business with husband Colin, 40, says he has experienced too many things to leave her in any doubt as to their validity.
She says: "When he was two, we were out walking when he started pointing and waving, saying, "Look, Mummy, there's a soldier, he's waving at us." There was no one there. He was so excited and animated. He then looked so disappointed when he told me the soldier had gone. I believed him. He was too little to make something like that up.
"Surprisingly, I didn't feel scared. I almost felt like it was a precious experience that someone from another life wanted to say hello."
Hollie also recalls another instance when Riley was around 18 months old. "I walked into his bedroom and he was having a conversation with someone. His language was limited, but he was talking and answering and gesturing with someone who wasn't there.
"I asked him who it was. He said it was Humpty. He kept on telling me for days afterwards that Humpty was there. At the time, our neighbour had just died, a man who was very overweight. I had never sung this nursery rhyme to Riley. Maybe he'd picked it up elsewhere, but I think he was talking to our neighbour."
Riley also had an imaginary friend at pre-school called George, who was so real to him that he was the only child he played with. She adds: "Yes, it could be nothing more than an imaginary friend, but in the context of these other things, I'm not so sure.
Celebrity psychic Honor Broxap believes such sightings should not be dismissed. 'We are all born with a sixth sense,' she says. 'Yet we stop using it as we get older. Children are much more believing, less questioning or cynical. They have not yet been conditioned to think that it's all just nonsense.
"You have to be careful that you don't over-exaggerate it. Yes, children do have a vivid imagination, but more often than not, there is some truth in it."
Clairvoyant medium and psychic artist Jackie Dennison agrees: "Children have imaginary friends. Maybe, it is just that, but perhaps it is sometimes more. They are very open to spirits and are unfazed by them. They take things in their stride. I believe we can also see layers of time, memories and echoes of what was once there."
Jackie says that this might explain the sheep in my cellar, and, with regards to Tilly and Alex, she tells me not to worry about them: "I think the fact that they're in your home is quite amazing. They are obviously happy that you're living there as a family."
Although I don't share this sense of wonderment, I'm starting to feel a touch more at ease as to whatever is going on in my home. Rosalyn is happy, and also very young. I'm sure, like Luca and Riley, these stories will start to tail off as her real world expands, and she won't remember much of what she tells me now.
Yet, although I've tried to dismiss it and laugh it off, there is a growing part of me that is no longer fully convinced that we're entirely alone in our home.