(or: my thought process documented while experiencing British driving)
I didn't even need to leave London's Heathrow airport on my way back from New York to experience the famous British driving. The shuttle from Terminal 4 to Terminal 1 was enough.
At first, I didn't quite know what felt wrong. I thought I must be feeling funny because of the lack of sleep last night due to my turbulent cross-Atlantic flight. Then, I realized that no, that can't be it. I began to slowly formulate the thought that the shuttle drivers had a funny way of driving, still not quite piecing it together in my mind that they were on the wrong side of the road.
Now before you say "duh! we all know that," I'd like to point out that unless you're actively and comprehensibly thinking about seeing drivers on the other side, it comes as a consciously expected, yet subconsiously jarring sight. I kept my calm and carried on, as the poster goes.