I was on my way home from work today, descending the last set of stairs to the south bound Northern Line platform at Leicester Square, when something ahead of me caught my attention. Watching my feet as I descended the stairs, something vaguely familiar entered my peripheral vision, and I looked up to focus on it, just in time to see a very shapely arse in a thin pair of tracksuit bottoms disappearing around the bend of the stairs.

This was no average ass. This was the proto-ass, of which all other asses are saggy, mis-shapen, inferior imitations. It didn't jiggle, or swing, it just bounced like a solid rubber ball, shifting up and down only ever so slightly as it disappeared rapidly from view. My appreciation of its qualities was significantly aided by the tracksuit bottoms, which were, as they all are, paper thin, and made of a silky material which slides easily, revealing contours in motion.

I guess it couldn't have been somebody I knew, I thought to myself, in the final seconds as I hit the bottom of the stairs. I don't know anybody who would wear tracksuit bottoms on the tube. In fact, I don't know anybody with an ass that good, full stop -- well, except for maybe my ex-housemate of 2 years ago, B. B always used to wear micro-thin pyjama bottoms around the house, an item of clothing that betters even tracksuit bottoms for ease of arse-appreciation. But B used to get off work an hour before I now do, and last I heard, he wore a suit to work.

It must have just been the ass itself that caught my attention, I decided. It was a very nice ass though, one that might be worth some mild tube-stalking. Quite easily done, strolling along the platform casually, locating the object of one's interest on the platform and standing a discreet distance away from its owner, making sure one is down-tube of your subject, thereby providing you with an excuse to frequently glance in that direction as you check the tunnel for a train. Tube stalking is every Londoner's hobby. Nothing sinister, just light entertainment as you wait two minutes for your tube to arrive.

However, today was not a good day to travel the Northern. Some sort of failure earlier in the afternoon had trains on the Charing Cross branch running with big 7-minute gaps, a recipe for packed trains and impassable platforms. So as I turned left at the bottom of the stairs, I discovered the platform too full to move anywhere. The owner of the ass had been similarly stopped, and so was immediately in front of me. The arse-possessor had apparently decided, instead of squeezing through the crowds to move along the platform, he would just stop in the entrance, blocking anyone behind him.

At this point, a total of perhaps seven seconds have elapsed since my attention was initally drawn at the top of the stairs. Vaguely irritated by his inconsiderate decision, I decided to abandon my tube-stalking plans (impractical anyway on such a crowded platform) and push past him. As I did so, I turned to glance at the owner of the arse, to at least check if the face did the posterior any justice.

And found myself face to face with ex-housemate B, with whom I then had a very pleasant twenty-minute chat.

Long-distance peripheral vision ass-recognition. Another highly-developed skill that I nevertheless cannot include on my CV.