The 'Great Western' line was the Ealing and Shepherds Bush Railway, authorised 1905, and opened (for GW freight services) in 1917. Original plan - apart from a connection to the West London Railway at Viaduct Junction - was for a GW terminus at Shepherds Bush (for interchange to the CLR - now LU Central Line), this was superceded by a CLR extension to Wood Lane Junction (with the E&SB) with electrification and running powers for CLR trains thence to Ealing Broadway (service commenced 1920). Subsequently an additional pair of tracks was built from N Acton (junction with the GW Old Oak Common - Northolt (for GW&GC Jt) line, to permit segregation of GW and CLR/LT services, and closed/removed in the 1960s.
Considering all this, and what is marked on the 1915 (publication date - revision was 1912-14) OS 25inch maps linked above I am wondering how far the GWC site extended north, and so to what extent the map for Japanese-British exhibition of 1910 (also linked), which has a 1909 date, reflects what actually was - and so whether the railway in question was ever built, or had any existence beyond an ephemeral existance as a contractors' line. If it was, it was either south of the (later, but not by much) E&SB line, or its track bed was reused by the E&SB