Uncle Frank was recently reminiscing about the days of his youth, when he worked as a porter at Smithfield Market. He took the Circle line every day between Victoria and Farringdon, morning and evening. "You know, it’s a funny old thing," he said, "but I noticed that in the morning I usually went via Embankment, but in the evenings I usually went via King's Cross. I spent 80% of my life going anti-clockwise!"
He was always good with numbers and had realised that, although he arrived at the station at random times going to and from work and just took the first Circle Line train that came, he was on the southern route 7 days out of 10 in the morning and the northern route 9 days out of 10 in the evening. "Of course," he said, "in those days the tube always ran on time. You could set your pocket watch by it."
If the trains really were on schedule and Frank arrived randomly at the stations, what accounts for the heavy bias to the inner circle?
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