I used to live in a typical UK ex-council house. Every home on my street looked exactly the same, from inside and outside. I was hesitant to move there and didn't settle in for years, but after a few years I made friends, and was old enough to hang out wherever I wanted. I got my own bedroom, which was downstairs in what used to be a dining room. I think that's what changed my opinion of living there. It's not ideal to share a bedroom with your younger brother when you're fifteen, and it was cool to have a floor all to myself during the night.

The only unsettling thing at the time was the heating pipes during the night. As soon as the boiler turned on, those pipes banged so loud. My friend warned me it wasn't normal for them to bang like that. He was convinced it was a ghost or something, and only slept over once. His whole attitude changed around me after that night. We went from close friends to acquaintances in a week. Every time he looked at me I could tell he was thinking about that night. There was a fear in his eyes. But I couldn't understand why some banging pipes would lead him to have some sort of post-traumatic stress. I brought it up once, and all he said was, "It's just the way it sounded. It wasn't pipes banging," and gave me a blank stare. At the time I thought he might have been embarrassed about wanting to go home in the middle of the night and had made up a story. But he'd stuck to this story for a couple of years.

My room was a bit strange. There was a big, frosted glass door between my bedroom and the living room, so my parents put a false wall either side of it so we could more easily resell the house. It made my room look weird because the area where that door used to be jutted out from the rest of the room like an alcove, so I filled it with a wardrobe that fit in there perfectly to make my room look square. The door I actually used for my room was on a double frame which came out into the kitchen. We decided to leave one door permanently locked and treat it like a wall. As unconventional as my room was, it worked for me and I was happy.

The hidden glass door as well as the constantly locked door, which I referred to as the "wall door," would rattle at the slightest movements. When the pipes rattled, so would both these doors at opposite ends of the room. So I wasn't surprised that my friend freaked when he stayed over that night. But every noise had a valid explanation, or so I thought.

One summer, between finishing secondary school and starting college, I decided to start having late nights. A late night for me prior to that decision was midnight. I remember I'd think, 'Oh god, It's now another day,' then go to bed feeling irrationally guilty. I guess I used to love my sleep as a kid. So at sixteen, I rebelled against myself and would challenge myself to stay up as late as possible. I'd usually be in bed by 1 AM or 2 AM latest, but one night I decided I would stay awake all night.

I did manage to stay awake all night. Even though I was exhausted and desperately needed to sleep. There was no way I could sleep after hearing that noise. It's hard to explain the sound, but it didn't invoke terror. It wasn't until a few years later that I could describe how that noise made me feel. When I read the definition of the word "despair":

The complete loss or absence of hope.

That's how it sounded.

That night was warm, so the heating stayed off. The doors didn't rattle. The house was silent and I was reading, lying on my bed. It started by sounding like a fingernail stroking the wall on the other side of the room. I convinced myself I was hearing my brother shuffling in his sleep right above me. But then it sounded like a whole hand stroking or wiping the other side of the wall from me, right next to my wardrobe where that glass door was hidden. It sounded soft. It actually sounded sad. And it definitely wasn't coming from above me.

It didn't stop when I plucked up the courage to go over. I put my ear to the wall and could hear the gentlest movements from the other side. It was like barely being close enough to a calm lake to hear the water caress the shore.

And the steady shuffles filled me with despair. All the happiness I'd felt that night, all the good things of my life left me, and I could tell whatever was making the noise on the other side of the wall felt more despair than I could ever have imagined. There was no hope in those brushing strokes.

Still in a trance, I decided to walk into my living room and see what was making the noise on the other side of the wall. My heart sank when I went through into that room. It had never occurred to me before that the wall in my room had a wardrobe in an alcove, but this side of the wall was completely straight. The house had a chimney shaft I had failed to recognise for years. All at once I realised the brushing was coming from inside that sealed column in the middle of my house that I had never even realised existed.

After an hour it had stopped. I lay awake staring at the ceiling until morning. The noise was so faint I could never tell if it was starting again or my memory was replaying it. I learned to tell the difference by the way I felt when I thought I heard it. If it was truly there, my whole body would feel heavy. Even the air in the room would feel too thick to breath. And the despair would creep up my body slowly, moving from my feet to my head.

Thank God I was moving house a month after that incident. I learned to sleep with earplugs and slept out every night possible until moving day. I couldn't bring myself to tell anyone about what was going on in the cavity. At the time, I couldn't even describe how it made me feel. I even wondered if I was hallucinating due to the stress from moving house.

On the moving day I volunteered to move everything from the loft into the van. We didn't go in there much, so it was a case of taking empty boxes up and filling them with anything worth keeping or selling. I'd never really been up there before, and it didn't click in my head that the chimney shaft would be there. Once I got up there and saw it, my heart dropped.

As I looked at it I noticed a brick was missing at eye level. I could actually see into the shaft. The urge was too great. I had to see whether I was hallucinating or not. I grabbed a cardboard box ready for the van and stood on it to get an angle where I could see the bottom of the chimney two stories below. As my eyes adjusted, I could see a small humanoid figure just sat there, looking up at me.

I saw two bright eyes of pure pale blue, with no whites or pupils, staring at me. Its eyes were small and they looked right at me. Its grey, bony hand reached up the side of the stone wall towards me with touches lighter than snowfall. Then the hand slowly slid down the bricks, and that terrible noise followed. I remember feeling absolute dread, then nothing.

The next thing I remember is my dad helping me up from the landing floor, under the loft hatch. He said I must have missed my step and fell right down the hatch, and was lucky to have just sprained my ankle. I didn't tell any of my family what I'd saw.

This happened a few years ago now but the scariest part has only became apparent recently. The more I try to remember that creature in my mind, I swear, the more it looks like a child's skeleton.