I Believe In Coincidence

Having grown up in a small Irish town it took me some time to adjust to life in London as a student. I was intrigued by how lonely one could feel in a large city, surrounded by millions. I took to going out for evening walks in the near-deserted suburban streets, and was amazed by how startled random passers-by were when I said hello to them, as I would have at home; almost as if I was going to attack them.
One evening I noticed a group of long-haired youths standing at a corner but hardly gave it a second thought, taking the jeers that came my way as harmless banter. It was only when they surrounded me in a threatening way that I realised there was an imminent danger of getting beaten up. Suddenly their leader stopped dead and called out my name! He was a guy I used to be friendly with back home. His followers melted away looking sheepish. What were the chances of that coincidence?