The East Coast Main Line (ECML) is a 393-mile long (632 km) major railway link between London and Edinburgh via Peterborough, Doncaster, York, Darlington, Durham and Newcastle; it is presently electrified along the whole route. The route forms a key artery on the eastern side of Great Britain and is broadly paralleled by the A1 trunk road.
The original line was built during the 1840s by three separate railway companies, the North British Railway, the North Eastern Railway, and the Great Northern Railway. During 1923, the enactment of the Railway Act of 1921 led to these three companies amalgamating together to form the London and North Eastern Railway (LNER). The route was the primary line of the LNER, who competed against rival London, Midland and Scottish Railway (LMS) for long-distance passenger traffic between London and Scotland. To this end, LNER's chief engineer Sir Nigel Gresley designed a number of iconic Pacific locomotives, including the famous steam locomotives "Flying Scotsman" and "Mallard". While running on the ECML, Mallard achieved a world record speed for a steam locomotive, having attained a recorded peak speed of 126 miles per hour (203 km/h) while traversing the Grantham-to-Peterborough section.
On 1 January 1948, the LNER and the ECML alike were nationalised by the government of the day, and operated by the state-owned British Rail. During the early 1960s, the line's steam locomotives were replaced by Diesel-electric counterparts, such as the powerful high-speed Deltic locomotives, while sections of the route were upgraded to enable trains to be routinely run at speeds of up to100 miles per hour (160 km/h). As the demand for higher speed intensified, British Rail introduced the High Speed Train (HST) between 1976 and 1981. During 1973, the prototype of the HST, the Class 41, was recorded as having achieved a top speed of 143 mph (230 km/h) in one test run on the line. Capable of 125 mph (201 km/h) in regular service, the HST proved to be a popular and iconic train on the line. During the 1980s, the line was electrified, allowing a new generation of electric traction, such as the Intercity 225, to be introduced.
Today, it links London, South East England and East Anglia, with Yorkshire, the North East Regions and Scotland and is important to the economic health of several areas of England and Scotland. It carries key commuter flows for the north side of London and also handles cross-country, commuter and local passenger services, and carries heavy tonnages of freight traffic. Services north of Edinburgh to Aberdeen and Inverness use diesel trains. During 1997, operation of services was passed into private hands. The main train service operator on the line is London North Eastern Railway, bringing the LNER name back into use, which took over from Virgin Trains East Coast in June 2018.
The core part of the route is the main line between King's Cross and Edinburgh, with the Hertford Loop used for local and freight services and the Northern City Line providing an inner suburban service direct to the city. The route has ELRs ECM1 - ECM9.
The ECML was originally developed and constructed out of the efforts of three independent railway companies. During the 1830s and 1840s, each of these firms had built their part of the route with the principal aim of serving their own areas, but also held the intention of linking each other's railways together to form an extensive through route that would span between the that became the East Coast Main Line. From north to south, these companies were: