London's Underground turns 150, and this programme marks the anniversary by tracing how the system began and how it still runs today. The centerpiece is a recreation: an old Metropolitan Railway steam locomotive hauling carriages along the network's original stretch of track, the line that opened between Paddington and Farringdon in 1863. At Farringdon station, preparations are underway for a royal visit, with Prince Charles and Camilla arriving to mark the occasion. Between these set pieces the film moves through the wider story of the Tube's growth, from its Victorian origins as a steam-powered novelty to the electrified, sprawling system that now carries millions of Londoners daily. It is a straightforward account built around one anniversary event rather than a deep archival excavation, but the pairing of a working steam engine on modern tracks with a royal ceremony gives a clear sense of how far the network has traveled from its nineteenth-century start.