I found a tube staff member today who was willing to explain to me the east/west bound train service on the circle line. Which for ythe most part makes a circle. Granted its got a tail but, and here is the confusing part, it is an enclosed loop, a circle if you will. Turns out, there's a ground zero station. All trains departing this station are either eastbound or westbound. It's all so simple now. And that station is Tower Hill. I wonder if this is a fact that all Londoners just know or something you have to learn. Like the fact that Alan Partridge isn't a real journalist. Or that Bank and Monument are for all intensive purposes, the same station. And that pressing the doors open button on the tube reveals you for the tourist that you are.
