Source: Ministry Of Transport, Successive Issues Of "Railway Statistics"
This NBER data series q03074 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: q03074
Release: NBER Macrohistory Database
National Bureau of Economic Research, Wagon-Miles, Total, Loaded and Empty for Great Britain [Q03074GBQ458NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q03074GBQ458NNBR/, July 28, 2015.