The other routes are the Chatham Main Line which runs along the north Kent coast to Ramsgate or Dover via Chatham and High Speed 1 which runs through the centre of Kent to the coast at Folkestone where it joins the Channel Tunnel.

As a cost-cutting measure, authorisation was secured in 1837 to make the junction with the London and Croydon Railway at Norwood, Surrey.

Parliament suggested that further savings could be made by avoiding having lines running in parallel valleys for 12 miles (19 km) if the SER were to make its junction further south.

The London and Brighton took advantage of this to ensure that gradients would be kept as shallow as possible, even at the expense of substantial earthworks and a mile-long tunnel at Merstham.

[2] Leaving the Brighton line, the railway took a direct route to Folkestone; plans to serve Maidstone were abandoned.

[13] East of Shakespeare Tunnel, a low trestle bridge was built across the beach to gain access to Dover.

[15] In May 1844, permission was gained to build a railway from Ashford to the Isle of Thanet, serving both Margate and Ramsgate.

[21] Both Dover and Folkestone provided access to the English Channel, and thus to the French ports of Calais and Boulogne.

[22] At Folkestone, the Pent Brook stream that ran through the Foord Gap had built up a spit of shingle, which acted as a breakwater and provided an anchorage.

At Dover, the River Dour had formed a shingle spit and thus a small harbour which required constant dredging to keep open.

They approached the Harbour Commissioners for permission to buy the desired site, but were refused on the grounds that they had not built on land they had previously purchased.

[31][26] In 1857, a new direct connection was put in at Tunbridge Junction, enabling trains to reach Hastings without reversing.

[35] This "cut-off" line, 24 miles (39 km) in length, reached Chislehurst & Bickley Park on 1 July 1865.

This station was replaced with a new one 600 yards (550 m) further south, which opened on 2 March 1868 when the line was extended to Orpington and Sevenoaks.

Proposals to extend this, or to build a line from Shorncliffe which would have passed under the Foord Gap Viaduct, to Folkestone Harbour, were defeated by local opposition.

It opened between Canterbury and Shorncliffe in 1889, stopping the LCDR from building its rival scheme, to which there was much opposition amongst the residents of Folkestone.

[47] The new company was short of locomotives and was glad to acquire five 4-4-0s that the Great North of Scotland Railway had ordered from Hurst, Nelson & Co Ltd, Glasgow but which subsequently had become surplus to their requirements.

At a meeting in 1913, SECR chairman H. Cosmo Bonsor said that the time was not right for the company to incur the heavy expenditure of electrification.

With the passing of the Trades Facilities Act 1922, the SECR proposed to electrify a number of lines in three stages.

On 27 June, new four aspect colour light signals were brought into use between Cannon Street, Charing Cross and Borough Market Junction.

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.

[69] 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.

[70] In 1954, Charing Cross, and to a lesser extent London Bridge, were remodelled to enable them to handle 10-coach trains on the suburban network.

On 5 April 1957, a fire destroyed the signal box at Cannon Street and severely affected the operation of trains.

This allowed the abolition of 32 signal boxes, with eleven more reduced to occasional use and one being manned during morning peak hours only.

[citation needed] Completion of the scheme would allow the phasing out of steam from the Eastern area of the Southern Region of British Railways.

Prior to construction of High Speed 1, also known as the Channel Tunnel Rail Link (CTRL), services ran over the South Eastern Main Line to Petts Wood, leaving at Chislehurst junction onto the Chatham Main Line.

The CTRL was built alongside the line to Ashford where is joined in to gain access to the existing station.

The CTRL diverges west of Ashford to pursue a separate route to its new London terminus (St Pancras).

Picturesque and unfamiliar sights (to visitors) on the line are oast houses, traditional farm buildings used for drying hops, whose conical roofs are tipped by distinctive cowls.