page_title: South Eastern main line
section_title: Electrification
hierarchical_section_title: South Eastern main line / History / Electrification
caption_attribution_description: Multiple-Unit Electric Train and Car Sheds at Orpington, S.R. Two three-car "sets" with two trailer coaches between Photo: Southern Ry.
context_page_description: The South Eastern main line is a major long-distance railway route in South East England, UK, one of the two main routes crossing the county of Kent, going via Sevenoaks, Tonbridge, Ashford and Folkestone to Dover. The other route is the Chatham main line which runs along the north Kent coast to Ramsgate and Dover via Chatham.
context_section_description: In 1903, the SECR obtained powers to electrify their lines. At a meeting in 1913, SECR chairman H. Cosmo Bonsor expressed the opinion that the time was not right for the company to incur the heavy expenditure that electrification would incur. The outbreak of war meant the postponement of any plans to electrify suburban lines. With the passing of the Trades Facilities Act 1922, the SECR proposed to electrify a number of lines in three stages. The SEML was to be partly electrified as follows - Charing Cross and Cannon Street to Orpington as part of Stage 1. Orpington to Tonbridge as part of Stage 2, which also included the electrification of the former SEML between Redhill and Tonbridge. Both stages only covered the working of local passenger trains on the lines that were electrified. Stage 3 was to extend the working to through passenger trains and freight. Permission was sought in 1922 to build an electricity generating station at Charlton, London. This was refused by the Electricity Commissioners, who insisted that the company bought electricity from an existing supply company. Objections to this by the SECR were not entertained. On 1 January 1923, the SECR became part of the Southern Railway (SR). 
  The SR decided that the electrification system was to be 660 V DC third rail. The first station on the SEML to see electric trains was Orpington, which was the terminus for electric trains from Victoria via Herne Hill and Shortlands. public services commenced on 12 July 1925. In preparation for Stage 2 of the electrification, the lines between Charing Cross and Metropolitan Junction were remodelled. Semaphore signals were replaced by colour light signals, with a new temporary manual signal box provided at Charing Cross. The lines serving Cannon Street were electrified. Electric trains were due to start on 1 December 1925, but power supply problems meant that the introduction of electric trains from Charing Cross and Cannon Street to Orpington was postponed until 28 February 1926. Cannon Street was closed from 5–28 June 1926 for alterations to the track layout and platforms. On 27 June, new four aspect colour light signals were brought into use between Cannon Street, Charing Cross and Borough Market Jn. New power signal boxes came into service at the two termini, but Metropolitan Jn remained a manually-worked box, although it was provided with a new 60-lever frame. With the introduction of the new service on 28 June, a new station was opened at Petts Wood. On 30 June 1929, four-aspect colour light signals were introduced between New Cross and Hither Green. New power signal boxes were provided at St Johns and Parks Bridge Jn, enabling seven manual boxes to be abolished. On 1 December 1929, four-aspect colour light signals were introduced between Spa Road and New Cross. A new power box at North Kent East Jn allowed the abolition of seven more manual boxes. The increased services provided by electric train meant that there were fewer paths available for freight trains to reach the marshalling yard at Hither Green. Therefore, the Greenwich Park Branch Line, which had closed on 1 January 1917 and thereafter was only used by freight trains as far as Brockley Lane, was brought back into use on 30 June 1929 as far as the point at which it crossed the SEML, a new spur being provided to give access to Hither Green. The reopened section of line was also electrified and provided with four aspect colour light signalling.
  In 1934, it was announced that the electrification of the SEML would be extended to Sevenoaks, including the loops at Chislehurst Jn. Electric services from Sevenoaks began on 6 January 1935. In February 1936, it was announced that the SR intended to extend electrification of the SEML to Tonbridge, as part of a scheme to electrify the Hastings line. In February 1937, it was announced that this part of a wider electrification scheme would be completed in January 1939. However, in February 1938, it was announced that the Hastings electrification had been abandoned due to the cost of having to either build dedicated rolling 
caption: Electric multiple units at Orpington, 1928. Two 3-car units sandwich a 2-car trailer set.
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