Partly because of disagreements with the Metropolitan Railway (Met R) over use of their tracks at the southern end of the route, the company built the Great Western and Great Central Joint Railway joint line (1906) from Grendon Underwood to Ashendon Junction, by-passing the greater part of the Met R's tracks.Apart from a small freight branch to Gotham between Nottingham and Loughborough, and the "Alternative Route" link added later (1906), these were the only branch lines from the London extension.
Several tunnels had to be built, the longest of which was the 2,997 yards (2,740 m) Catesby Tunnel.
Many miles of cuttings and embankments were also built.
The GCML was very much a strategic line in concept.
It was not intended to duplicate the Midland line by serving a great many centres of population.
The original estimated cost for the construction of the line was £3,132,155, however in the event it cost £11,500,000 (equivalent to £1,188,010,000 in 2016), Three special corridor trains, forming part of the new rolling stock constructed for the new line, were run from Manchester, Sheffield and Nottingham to the terminus at Marylebone for the inaugural ceremony.
A lunch for nearly 300 guests was provided, and then the trains made the return trip.
Instead it was intended to link the MS&LR's system stretching across northern England directly to London at as high a speed as possible and with a minimum of stops and connections: thus much of its route ran through sparsely populated countryside.
Starting at Annesley in Nottinghamshire, and running for 92 miles (148 km) in a relatively direct southward route, it left the crowded corridor through Nottingham (and Nottingham Victoria), which was also used by the London and North Western Railway (LNWR), then struck off to its new railway station at Leicester Central, passing Loughborough en route, where it crossed the Midland main line.
Four railway companies served Leicester: GCR, Midland, GNR, and LNWR.
Avoiding Wigston, the GCR served Lutterworth (the only town on the GCR not to be served by another railway company) before reaching the town of Rugby (at Rugby Central), where it crossed at right-angles over, and did not connect with, the LNWR's West Coast Main Line.
He grew tired of handing over potentially lucrative London-bound traffic to rivals, and, after several unsuccessful attempts in the 1870s to co-build a line to London with other companies, decided that the MS&LR needed to create its own route to the capital.