Series Is Presented Here As Two Variables--(1)--Original Data, 1921-1948 (2)--Original Data, 1947-1952. Data Cover All Railway Lines. Source: Central Statistics Office, Monthly Digest Of Statistics.
This NBER data series m03011ab appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: m03011ab
Release: NBER Macrohistory Database
National Bureau of Economic Research, Passenger Journeys Originating, British Railways for Great Britain [M031ABGBM428NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/M031ABGBM428NNBR/, June 3, 2015.