The South Eastern Railway (SER) was a railway company in south-eastern England from 1836 until 1922. The company was formed to construct a route from London to Dover. Branch lines were later opened to Tunbridge Wells, Hastings, Canterbury and other places in Kent. The SER absorbed or leased other railways, some older than itself, including the London and Greenwich Railway and the Canterbury and Whitstable Railway. Most of the company's routes were in Kent, eastern Sussex and the London suburbs, with a long cross-country route from Redhill in Surrey to Reading, Berkshire.

London is the capital and largest city of both England and the United Kingdom, with a population of around 8.8 million, and its metropolitan area is the largest in Western Europe, with a population of 14.9 million. It stands on the River Thames in south-east England at the head of a 50-mile (80 km) estuary down to the North Sea and has been a major settlement for nearly two millennia. The City of London, its ancient core and financial centre, was founded by the Romans as Londinium and retains its medieval boundaries. The City of Westminster, to the west of the City of London, has for centuries hosted the national government and parliament. In the 19th century, London grew rapidly, becoming the world's largest city at the time, as it expanded and absorbed the neighbouring county of Middlesex, and parts of Surrey and Kent. In 1965 it was combined with parts of Essex and Hertfordshire to create the administrative area of Greater London, which is governed by 33 local authorities and the Greater London Authority.