The West Coast Main Line (WCML) is one of the most important railway corridors in the United Kingdom, connecting the major cities of London and Glasgow with branches to Birmingham, Manchester, Liverpool and Edinburgh. It is one of the busiest mixed-traffic railway routes in Europe, carrying a mixture of intercity rail, regional rail, commuter rail and rail freight traffic. The core route of the WCML runs from London to Glasgow for 399 miles (642 km) and was opened from 1837 to 1881. With additional lines deviating to Northampton, Birmingham, Manchester, Liverpool and Edinburgh, this totals a route mileage of 700 miles (1,127 km). The Glasgow–Edinburgh via Carstairs line connects the WCML to Edinburgh. However, the main London–Edinburgh route is the East Coast Main Line. Several sections of the WCML form part of the suburban railway systems in London, Coventry, Birmingham, Manchester, Liverpool and Glasgow, with many more smaller commuter stations, as well as providing links to more rural towns.

Inter-city rail services are express trains that run services that connect cities over longer distances than commuter or regional trains. They include rail services that are neither short-distance commuter rail trains within one city area nor slow regional rail trains stopping at all stations and covering local journeys only. An inter-city train is typically an express train with limited stops and comfortable carriages to serve long-distance travel.