The line and junctions were historically important as they connected the industrialised areas of Lancashire and Yorkshire.

[4] Initially, the route, which was part of the Standedge Line (the modern Trans-Pennine Line) was to have run through Mirfield on separate tracks, but the L&YR acknowledged that it could not oppose the route, so accepted the LNWR having running powers between Heaton Lodge and Thornhill.

[7][8][9] The 2.5-mile (4 km) section of line between Heaton Lodge and Mirfield was constrained by a two-track bridge over the River Calder.

[15] At the same time, the slow Calder Valley lines west of Heaton Lodge Junction were used for wagon storage.

[14] A further fall in traffic saw the double-track dive-under reduced to a single line, and the line between Heaton Lodge and Thornhill rationalised into a reduced three-track railway in 1988, with three platforms at Mirfield railway station.

[20] With the gauge clearance, track reinstatement, the re-siting of Mirfield and Ravensthorpe stations, and the electrification of the route, the final bill for the section between Dewsbury and Huddersfield is expected to be £3 billion (estimated in 2023).