Source: Ministry Of Transport, Successive Issues Of "Railway Statistics"
This NBER data series q03075 appears on the NBER website in Chapter 3 at http://www.nber.org/databases/macrohistory/contents/chapter03.html.
NBER Indicator: q03075
Release: NBER Macrohistory Database
National Bureau of Economic Research, Loaded Wagon-Miles for Great Britain [Q03075GBQ458NNBR], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/Q03075GBQ458NNBR/, August 27, 2015.