Just to the right of the AdSense screen near the top end of Platform 1 and its neighbouring billboard, there is a rectangular recess on the other side of the tracks. It appears to be there so that someone who has fallen or jumped off the platform can escape an oncoming train. I can't imagine what else it might be for, since there doesn't seem to be any way to get to the recess apart from stepping off the platform, skipping over the rails (careful not to trip now) and clambering up a metal step.
The recess is perhaps a metre and a half wide and deep, and twice as tall with an arched top. It is closed on four sides (back,left,right,bottom) by the ashy black walls that line all the train tunnels. If you were to stand on it, beneath your feet would likely rattle and screech an unremarkable metal grate.
I make this speculation because I have heard a rattle and screech on that particular grate. I was leaning against the wall across from the recess, eating a blueberry muffin and waiting for my train, when I heard it. I looked to my left, and there was a businessman reading his newspaper. To my right, a woman fishing her mobile phone out of her bag. Straight ahead, was a small wizened man who straightened up after dropping down from the top portion of the recess. From where he originated I don't know, but he seemed pleased that he was noticed.
He scrambled down from the alcove and, without looking for a train, skipped over the tracks and up onto the platform. He had a hairless round face and small twinkling eyes of indeterminate color. His clothing was a non-descript brown. He peered up at me from a level just above my knees.
"Hello," I stuttered.
He didn't reply but handed me a cool and strange gold coin. I studied it carefully, and looking down again from my palm found him vanished. I tucked my hand into my coat pocket and stepped onto the train home.
I didn't think about it again until I was taking my coat out of the closet a few days later. Feeling a small unyielding lump in my pocket I slid my hand into the fabric. I pulled out a small bottlecap with a brand of drink I had never seen before printed on its surface.