The London Underground, colloquially known as “the Tube,” is a transit system serving London and the surrounding environs. It is the oldest underground railway and currently the 7th largest such transit system in the world. Building on the Metropolitan Railway that developed in the 1830s, the first underground railway carriage began operating in 1863. As of 2023, 11 rail lines serve 272 stations, transporting an average of 3 million passengers a day and over a billion a year, both below and above ground. Many processes are automated, including payment, announcements, and driving.

Adumbrating the Tube is a larger system of railways that connects London’s environs to cities beyond, including the South Western Railway, which operates the train Iona takes. Iona boards on a small spur at Hampton Court that runs through Thames Ditton station before joining the main tracks and its stops at Surbiton, Berrylands, New Malden, Raynes Park, Wimbledon, Clapham Junction, and Vauxhall, with its terminus at Waterloo. Waterloo is the largest and busiest London terminal, and it connects to the London Underground station of the same name.

The ride on Iona’s train typically takes between 34 to 41 minutes. Clare Pooley reveals in the Author’s Note that she has taken some liberties with details of the train system.