The Lancashire and Yorkshire Railway (L&YR) was a major British railway company before the 1923 Grouping. It was incorporated in 1847 from an amalgamation of several existing railways. It was the third-largest railway system based in northern England (after the Midland and North Eastern Railways).
The intensity of its service was reflected in the 1,650 locomotives it owned – it was by far the most densely trafficked system in the British Isles with more locomotives per mile than any other company – and that one third of its 738 signal boxes controlled junctions averaging one every 3+1⁄2 miles (6 km). No two adjacent stations were more than 5+1⁄2 miles (9 km) apart and its 1,904 passenger services occupied 57 pages in Bradshaw, a number exceeded only by the Great Western Railway, the London and North Western Railway, and the Midland Railway. It was the first mainline railway to introduce electrification of some of its lines, and it also ran steamboat services across the Irish Sea and North Sea, being a bigger shipowner than any other British railway company.