This piece was originally written in April 2003 for issue 1 of Smoke: a London Peculiar and re-worked in June 2008 to launch the original Danger: Void Behind Door blog.

One long-ago evening, shortly before midnight, I found myself sitting in tearful confusion at the back end of the southbound Bakerloo Line platform at Waterloo waiting for a train to come and carry me one stop home to Lambeth North.

Tears and confusion had, I’m afraid to say, become something of a regular feature of my relationship with – well, let’s just call her K. And, over the preceding few weeks, I’d spent so much time shivering by the ticket barriers at Lambeth North waiting for her to turn up, or to not turn up, as the fancy took her, that her sudden recollection at closing time on this particular evening that she had a friend staying over and thus had to go back to her own flat rather than mine, had had a certain grim inevitability to it.

The numbing predictability wasn’t really much consolation, though. And, as I sat there on the plastic bench, trying to find solace in the chunkier, less-easily-blurred print of the Easyjet advert on the wall across the tracks, I couldn’t stop myself thinking back to how, only that morning, I’d once again lingered pathetically beside those selfsame barriers in faint hope of just one tiny off-the-shoulder glance backwards as she’d glided towards the lifts and her desk at the BBC.

This was the point at which I found my bleary eye suddenly caught by the words on a small yellow panel at my side.

DANGER: VOID BEHIND DOOR

They were, to be honest, words I’d read a hundred times. I’d usually read them from inside a waiting train, though, and, being a rational sort of chap, never really given them much thought: after all, even had I been prepared to countenance the possibility that not only might some sort of diabolical netherworld actually exist, but that its formless howling darkness might in places lie mere inches below the surface of our own familiar realm, the idea that a functioning portal into such infinite mind-terrorising nothingness could be found behind a small yellow door on the southbound Bakerloo Line platform at Waterloo was utterly preposterous. Obviously this didn’t help to explain what the words did mean but, by this stage of my journey, I’d generally have more important things on my mind than obscure TfL signage, such as whether to pop into Costcutter for some milk.

On this melancholy evening, however, I had no thought for chiller cabinets. And, as I gazed at those hard black letters, I remembered something else that had always puzzled me. Whenever I did linger in the booking hall at Lambeth North to watch K’s carefree morning sashay away from the ticket barriers – a not uncommon occurrence, in truth, as red wine, it turns out, often prevents recall of last-train times – there was always a point at which she slipped from direct sight and I had to turn my eyes to the nearby CCTV monitor, eagerly anticipating her arrival inside its fuzzy grey image of lift doors. And here’s the thing: although those doors would have been at most a dozen size-4 steps away from the point at which she disappeared, the screen always remained empty for six whole seconds.

It had, as I say, always been a source of bafflement. But now, suddenly, in my emotionally-heightened state, the explanation seemed obvious: at some point between the ticket barriers and the lifts at Lambeth North station, SPACE AND TIME HAD BECOME DISLOCATED. To anyone actually making that walk – a five-foot-three Scottish brunette with eyes that sparkled like moonlight on the deep dark waters of the Esk in winter, for example – nothing would seem awry; but, to anyone watching, for six whole seconds, she would be… elsewhere. Where? Well, I couldn’t say for sure. But, as I sat there that evening listening to the singing of the tracks and the distant rush of air somewhere down the tunnel to my right, I became convinced that, were I to yank open that small yellow door at the very moment she disappeared, I would see her, trotting brightly across the eternal black void, mind on other things, still failing to look back.

Once I’d got home, I left a message on her answerphone, asking her what she thought.

It’s been nearly ten years now.