The paranormal (and in particular, ghosts) has held a fascination for me ever since I was a young child in short pants running around the green grassy fields and meadows of 1970s Lincolnshire. Some of my earliest memories involve tales of ghosts and nightmarish creatures that supposedly haunted old barns, dilapidated manors, and dark damp woods. My father, a man of rare intellect, insight, and logic, was a high-ranking airman who, at the time, was flying with the Royal Air Force. My mother, typical of the time, stayed at home to look after me and my siblings (which, in hindsight, was a fairly full-on job in itself given our precocious nature). However, don't let this fool you; my mother was also intelligent (if lacking my father's attention to detail). She was a qualified teacher, and a vastly competent pianist. Now, at this stage one might be wondering why this is of importance given our subject is ghosts. However, this will rapidly become clear.

Both my parents had a great love and interest in history, and this manifested itself in untold weekend trips where my mother would pack sandwiches and a Thermos and we'd all be bundled into an ancient black Humber sedan in which we’d drive off into the countryside, stopping at historic sites, ancient battlefields, Neolithic earthworks and monuments, stately manors, half-forgotten Second World War sites such as bunkers and gun emplacement, and above all, castles. And it was one particular castle that awakened my interest in ghosts, a castle that had its origins as a fortified manor house built in 1231 by Robert de Tattershall and then later rebuilt in brick sometime between 1430 and 1450 by Ralph, Third Lord Cromwell.

Today Tattershall Castle is one of the most important surviving brick castles of the mid-fifteenth, given that brick castles were far less common in England than stone (brick was chosen more often than not for its aesthetic qualities over defensive). It has been estimated that about 700,000 bricks were used to build the castle, which has been described as the finest piece of medieval brick work in England. However, this was not what grabbed my imagination. I was fascinated by the prospect of it being haunted, and as such, the castle has remained in my memory even since. Whether or not it is haunted is debatable, although I did write in my latest book Haunted Castles of England that, "[a]lthough seemingly quiet with regards to the supernatural, the castle is nevertheless said to be haunted by the ghost of a White Lady who walks the lonely battlements at night. Who she is, no one knows."

Haunted or not, Tattershall castle was the beginning of my interest in ghosts and the paranormal that took me from dog-eared books about the Bermuda Triangle and Eric von Daniken's Chariots of the Gods to tattered magazines with articles about Bigfoot and the Loch Ness Monster. However, in the end I was always drawn back to my favourite subject, ghosts. Why do they exist? Where can they be found? Why are some people apparently more susceptible to ghostly encounters? And most importantly, what are they and what is their purpose?

My quest, if one could call it that, has taken me from the isolation of the infamous Jamaica Inn on Bodmin Moor to the brooding serenity of Woodchester Mansion in leafy Gloucestershire. I have wandered the grounds of Port Arthur in Tasmania searching for the ghosts of Australia's convict past and have entered, with some trepidation, the softly swaying but ominous cornfields of Gettysburg where the ghosts of the American Civil War are said to still man their posts. I have descended the depths of Edinburgh Castle and have had a personal tour of the Ancient Ram Inn in the quintessentially but curiously named English town of Wotton-Under-Edge. I have sat in the quiet and brooding dungeons of Dunster Castle in Somerset and walked the grim, bleak corridors of the Old Melbourne Gaol. And during these visits I have been fortunate enough to have had a number of possible encounters with ghostly entities, not only sightings, but ethereal voices, strange night time rappings. and disembodied footsteps.

Without going into too much detail, I have seen what I consider to be a ghost, not once, but three times. The first was a shadowy monk-like figure in a room in the Dragon Inn in the Welsh border town of Montgomery; the second, a strange encounter with a small, frail, ghostly woman dressed in brown in the infamous Hellfire Caves in Buckinghamshire; and the third, which was also witnessed by my sister, a fleeting glimpse of a figure in a white dress that gave me the impression of a thin, middle age Victorian woman, who walked past an open door and disappeared.

Interestingly, I am often asked whether or not I believe in ghosts (which I most obviously do). However, I am what one could describe as a skeptical believer in that, although I believe in ghosts and the supernatural, I like to think that there is a rational explanation for most occurrences. As such, when I write about the phenomena I attempt to only present the facts or stories as I find them, and not blunder off into sensationalism. (Besides, ghosts are somewhat sensational enough without adding to the mix.)

Over time, history has shown us that ghosts and the supernatural appear to be almost commonplace and that a large percentage of people in the Western world, indeed from all races and religions, not only believe in ghosts but claim to have experienced something of a supernatural origin at least once in their lifetime. Indeed, how is it that so many people with no connection to each other and over such a length of time report such similar ghostly happenings in cases such as The Tower of London, the Enfield Poltergeist, the Spaniard's Inn, the White House or Gettysburg? Surely all these witnesses cannot have invented the almost exact same story every time over a period of years and years? Can all these people be wrong? Have they simply misinterpreted what they have experienced? Are they deluded or deranged? Of course, one could argue that, in many cases, yes. And yet, no matter how hard we try to filter out the explainable, the suspect and the truly outrageous, there still exists thousands, if not tens of thousands of cases that defy explanation. As such, one can only come to a single conclusion, as unpalatable or irrational as it may seem to some, and that is that ghosts must exist.

However, having said this places us in the unenviable situation whereby we now need to justify not only our belief that ghosts exist, but what ghosts are. Of course, answering this question has consumed many writers and scholars for hundreds, if not thousands of years, stretching back before the written word to a time when oral story telling was our main means of communication. Which begs the question, did Neanderthal man see Neanderthal ghosts? Or did he see the ghosts of Cro-Magnon man? Somewhere at some time in human evolution we developed self-awareness and consciousness plus the ability to not only adapt to our surroundings but to adapt our surroundings to us. And with this ability we also developed a basic spiritualism. We understood that people lived and people died, and at some period of time we started to honor people in death through burials and ceremonies. Is this when we, as a species, became aware of ghosts?

In 1957, a grave dated at 60,000 to 80,000 years before present was found in a cave in northeastern Iraq. It contained the skeleton of a Neanderthal man, and although the burial was considered somewhat crude, archaeologists discovered pollen. The man had been buried with flowers. This leads us to the inevitable conclusion being that early man, both Homo Erectus and Neanderthal, believed that there was something more to life than just living, and that in death the soul, or essence of the person, remained.

However, archaeology and evolution aside, if ghosts are so predominant then why can't science explain what is going on?  Is it possible that we are somehow predisposed to believe in ghosts, or even hardwired through evolution to see them? Were the imaginary friends of our childhood really imaginary? Or were they, in fact, ghosts, entities that we as adults have somehow lost the ability to see? Interestingly, Will Storr in his insightful book, Will Storr versus the Supernatural, relates a short but thought-provoking story about a friend of his who had a child with an imaginary friend (not a strange situation in any circumstance). However, according to Storr, one day the mother, hearing her child speaking to the imaginary friend in another room, opened the door and was shocked to see the imaginary friend, who then rapidly disappeared before her eyes.

If we are to believe Storr's recounting of this story, can we suggest that mediums and psychics still possess this ability to see and converse with spirits? And if so, have we as adults somehow lost this previously innate ability to not only see, but to converse with these spirits? I offer no answers, but the question is intriguing at the very least. And what of places that seem to convey a certain intangible feeling? Without doubt everyone reading this has visited such a place, whether it be a cemetery, an old church, an abandoned ancient battlefield, or a majestic, ruined castle. Who among us can truly say that they have not walked into a room, or have wandered along a dark, lonely road at night and have felt the hairs on the back of their necks rise and their heart beat faster?

Of course, none of this helps answer our original question, that being, what exactly is a ghost? Having said this, I feel it important that writers such as myself continue to put forward ideas about ghosts and their nature so as to provoke a response from others. And in these responses we may finally come to the realization that, not only are ghosts real, but what they actually are. For instance, popular culture assumes that ghosts are simply the spirits of the dead, somehow caught up in some inexplicable limbo for whatever reason, usually violent death, lost love, or other tragic circumstances. And yet, this is most obviously not true. As such we need to look at ghosts in a different light and move away from the idea that ghosts are exclusively returning spirits of the dead.

If we are to believe contemporary and historical reports, ghosts appear to exist in many forms, such as odd noises, unexplained lights, cold spots, drafts, object movements, smells, feelings, shadows, and occasionally human figures. Indeed, some even appear to exhibit intelligence whilst others are nothing more than a replay of some historical event, almost like a hologram, endlessly looping around the same actions again and again. And so, although we have a popular theory as to what a ghost is, we should begin with some sort of easy to understand, working definition of a ghost. As such, we can say that a ghost is a human, or sometimes animal figure or shape that cannot be logically physically present and has been witnessed by a person or persons. We can also therefore define a haunting as being a series of unexplained events or experiences in a certain specific location due to the suspected presence of a ghost or spirit.

But how is it possible that all of these are the same phenomenon? Could it be that some spirits are much stronger than others and are able to appear in a fully formed human figure while others can do no more than make a light dim or move a glass on a shelf? And what of poltergeists? Are they ghosts at all? Why, if a poltergeist can lift beds, throw objects, and move furniture, do they rarely manifest in a visible form? Surely something as powerful as a poltergeist would be able to do so especially when you think of other benign hauntings where people claim to see full bodily apparitions walking by but not disturbing their surroundings?

As a result, we must ask, if the entire phenomena and scope of ghosts and hauntings is so different, how did we arrive with the idea that all ghosts are just returned or returning spirits of the dead? For instance, could ghosts simply be people caught in a timeslip? Or are they really the spirits of the dead? Could it be that they are a build-up of energy, whether positive or negative, over time that somehow, under certain environmental of ecological conditions, be released on occasions as some sort of unexplainable three dimensional historical replay? Or could they simply be a misinterpretation of facts and events due to a number of factors such as over stimulation, suggestion, mental disorders, or fantasy? I suspect all of the above.

And this brings us back to my mother and father, who I can thank for my interest in the paranormal. As previously noted, they introduced me to history and culture and stories that opened my eyes and stimulated my imagination. Stories of Druids who danced around Stonehenge, knights who lived in magnificent stone castles, pirates who sailed the seven seas, and trolls that lived under Norwegian bridges and waited for unsuspecting billy goats. And ghost stories. What did the dank, grey fogs of Lincolnshire hide? What ungodly creatures lurked in the dark woods just across the meadow from our old, two-story house? What terrible ancient secrets did the murky waters of the Thames hold? Did the ghosts of long-dead plague victims rises slowly from their mass graves late at night when the moon was obscured by dark clouds and the air was still and cold? And further north, where the trees are thinner and the mists of time obscure the barbarity of the times and the ruins of Hadrian's Wall stretch like a cold stone ribbon across the countryside; here one can believe that the ghosts of long-dead Roman centurions still stand watching for Pictish hordes to come rampaging across the grassy fields.

And of course, castles, those bastions of power and might, long regarded as prime settings for ghosts due to their long and unusually bloody histories that have seen war, pestilence, siege, death, torture, joy, and despair. They are places where death has stalked the lonely stone corridors, where prisoners have slowly rotted in dark, damp, rat-infested dungeons and oubliettes and where joyous unions have been forged and destroyed. Castles may be magnificent edifices to a glorious medieval past, but they are also a reminder of earlier, grim times of violence, bloodshed, and tragedy. With this sort of past, it is little wonder that, in these places, ghosts are real. Very real indeed.

And you know, even after all of this, my parents still don't believe in ghosts.