"So where did you see this ghost?" I asked, mildly amused by the tale being told by the old porter.

The other man grunted, clearly relishing the opportunity to spin a yarn. He must have noticed, but seemed prepared to ignore, the scepticism visible on my face.

"It always shows up in that stairwell behind the lecture theatres, at the upper ground level," he replied laconically.

The man I knew only as George was a wizened old gnome, wiry and bandy-legged. He struck me as surprisingly hairy about the ears and on the backs of his hands, which contrasted with the compact and polished dome of his head. He was apparently one of that group of men known as porters, who delivered the mail, moved the furniture and acted as general factotums to the academic staff at the University. Old George had told me that he had been in the Computer Science building ever since it opened, back in the 1970s.

In this day and age, the porters act as the security staff, and are on duty twenty-four hours a day. While any member of the faculty could come and go as they please, they rarely did and there were usually not very many people in the building in the middle of the night.

It was two in the morning, and we were standing in the otherwise empty foyer. For some reason, I only ever encountered George in the middle of the night. Perhaps it was his preference for the night shift. Tonight, the porter seemed to be in a garrulous mood. I fully admit that I was incredulous, entirely disbelieving, but the old man seemed to be utterly serious.

"It's always been there, as I recall. There were occasional sightings when I first came here," he continued, with a slight shake of his head at my youthful intransigence.

"Mind you, in those days, months or even years would go by with a visitation," he continued, "The apparition's appearances seem to be getting more frequent."

I shook my head but, before I could make any intelligible response, old George straightened from the slouch he had adopted.

"Well, I can't stand around here nattering all night," he muttered, "I've me rounds to do."

And with that, he stalked off down one of the darkened corridors, soon to be lost to sight.

I suppose I am still a student of sorts, now undertaking post-doctoral work in the School of Computer Science. The Computer building at the red-brick university I have hung around for more than a decade is itself a monument to 1970's structural design. The architectural vernacular of the time was for steel-reinforced concrete framework clad in - yes - red bricks with tall narrow windows fitted with darkened glass, arranged in serried rows on all four sides. The building has several floors above ground level where lecture theatres, classrooms and laboratories for practical work can be found, as well as rooms full of personal computers for use by students. The latter seem to be always in use, even in the middle of the night. It always amused me to see just one or two hunched figures, widely separated amongst the rows of quietly humming PCs.

The need for a large number of rooms must have given the building designers a headache, since much of the interior is a warren of corridors and staircases. The uppermost floors are occupied by spacious individual offices for the academic staff, close to their secretarial and administrative supporters, as well as much more cramped shared accommodation for the post-docs and research students.

Further down, there are extensive basements housing the air-conditioning machinery and various workshops and storerooms, as well as several large machine rooms. These house rows of metal cabinets, these days usually painted in fashionable shades of black, containing the central computers and peripheral machines which are even nowadays adorned with green and blue blinking lights.

I have always been something of a night-owl, preferring to stay up until the wee hours whether I am working or socialising. I always rise late in the morning, even then unable to function even then without at least one large mug of the poisonously strong black coffee I favour. I am not sure just why this is. Maybe I am naturally not a morning person, or perhaps this is just a legacy of years of being a university student.

My nocturnal working habits are by now familiar to the portering and security staff. I can frequently be found working late at night. It would not be unusual for me to stay in the building all night, finally emerging in the morning, blinking in the light. Then I would stumble to the bus stop for the short journey back to the terraced house I share with three other post-grads, all of whom are attached to other parts of the Faculty of Science and Engineering.

These night-shift hours had allowed me to acquire a nodding acquaintance with George the porter, who always seemed to be on night duty. It was not uncommon for me to come across him patrolling the darkened corridors and public spaces of the School.

I occasionally found myself wondering about the story he had told and, out of sheer curiosity, took to passing by the location George had described. The stairwell was quiet and out-of-the-way corner of the building. The complicated interior design meant that there was almost always no direct route between any two points, and it was generally not much out of my way to pass by regularly on my way to my office. "My office" sounds rather grand, especially as this is actually just a desk and a couple of filing cabinet drawers in a shared room in that far corner of the building.

With hindsight, it must have been unsurprising that I did finally see the ghost. One evening, not even particularly late - certainly well before midnight - I was making my way downstairs to the machine room, picking the route through the haunted stairwell quite automatically.

It was astonishing. The whole experience was exactly what I would have expected from folklore and children's tales. The first indication was a sudden chill, a drop in temperature which somehow did not quite feel like a malfunction in the air-conditioning. Then I caught sight of a vague shape, hanging in the air, as if a humanoid figure have been draped head-to-foot in a badly-washed white sheet. Whatever it was, it was hovering in the stairwell in such a position that taking the steps downwards would have brought me level with the spectre.

The figure had its back towards me, as far as I could tell. As I watched, I thought it made to turn in my direction but, before the movement had barely begun, the apparition faded into nothingness. The chill in the air dissipated just as rapidly, and I found myself standing mouth open and wondering whether I had imagined the whole thing.

The only thing that jarred with the bedtime storybook was that I did not feel in the slightest bit frightened. The ghost just was not scary. I was curious, intrigued even, and I resolved immediately to investigate further. That turned out to be easier than I expected. After that first sighting, the spectre always seemed to be there, sometimes plainly visible and at other times just the mere suggestion of a presence. Strangely, it was only apparent when I was on my own; on the rare occasions when I was in company, I always found the stairwell entirely uninhabited.

I made opportunities to talk with some of the other postgrads, and even some of the younger members of staff. But, having asked around a few times whether anyone sensed anything unusual or spooky in that stairwell, but mostly gave up after the number of strange looks I received.

I had heard that theory that ghosts are somehow representations - echoes projected through time - of a moment in a person's life, especially an intensely emotional moment close to death. Logically, this means that graveyards are the last place you should expect to find ghosts, since people almost never die there except under the - I hope! - rare circumstances of being buried alive.

From its beginnings in Victorian philanthropy and mock-gothic majesty, the University buildings had grown organically over ground previously occupied by rows of back-to-back terraced houses - a classic Coronation Street scene now bulldozed flat. The Computer Science building was in fact squatting on a foundation of broken bricks and torn-up cobblestones - the remains of homes for thousands of workers in the early ages of industrialisation.

These old houses must have seen any number of births, deaths and marriages over the years. I have seen black-and-white photos of the Computer building under construction, on posters decorating the otherwise bare breeze-block walls in out-of-the-way corridors. As I saw it, the level of that haunted stairwell was at the height of an upstairs bedroom of an old terrace - just the place where a bed-bound person might have lived their last, and died.

The haunting was beginning to prey on my mind and I felt I needed someone to talk to. I wanted to find some explanation of what I had witnessed.

Introduction Part 2