All passenger services run as all-stations shuttles between Redhill and Tonbridge, and are operated by Southern using Class 377 electric multiple units.

At the time of construction, east Surrey and west Kent were sparsely populated and most of the intermediate stations are some distance from the settlements they purport to serve.

Although the parliamentary committee scrutinising the plans was sceptical of the cost estimates for the embankments and tunnels required,[42] the South Eastern Railway Act was passed on 21 June 1836.

[43][f] The first board meeting of the South Eastern Railway (SER) took place on 2 July 1836,[44] chaired by Pascoe St Leger Grenfell.

Since the SER and L&BR would run alongside each other between Norwood and Purley, the act gave the two companies permission to share a single pair of tracks to avoid duplication.

William Cubitt was instructed to cooperate with Joseph Gibbs, the L&BR engineer, and to explore potential route changes that might result in cost savings.

[48][50] Agreement was reached in November 1838 for the SER to branch from the L&BR at Redhill and the revised plan was approved by act of Parliament on 19 July 1839.

[59] Initially the revenue generated was disappointing, but the SER anticipated that passenger numbers would rise once the railway began serving the channel ports.

Originally called "Reigate" and sited on Hooley Lane, it was resited to allow better interchange with LB&SCR services to-and-from Brighton.

[71][72] The scheme was initiated by Sir Henry Edwards, the former MP for Weymouth and Melcombe Regis, who had acquired land on both sides of the railway in the 1860s.

[40] The station was immediately adjacent to Leigh signal box, which had been commissioned in 1902 to reduce the length of the block sections between Penshurst and Tonbridge.

[90][91] In 1941, Tonbridge West Yard was opened to facilitate freight movements for the war effort[24] and in the same year, two-aspect colour light signalling was installed in the Penshurst area to increase the capacity of the line.

[92] The first Beeching report, published in 1963, recommended shutting all five intermediate stations between Nutfield and Leigh inclusive,[93] although a non-stop passenger service between Redhill and Tonbridge was to be retained.

Nicknamed "Tadpoles" and officially designated 3R, these diesel multiple units began operating an hourly stopping service between Reading and Tonbridge, calling at all stations except Winnersh and Earley, and requiring a reversal at Redhill.

[104][105][o] For three years from May 1986, Reigate became the western terminus for most trains running to Tonbridge via Redhill, with services only extended to Reading at peak times.

[105][108] Resignalling of the line began with the section between Redhill and Godstone (exclusive), with control transferred to Three Bridges Area Signalling Centre on 12 May 1985.

[112] As part of the works to connect the tunnel to the existing UK rail network, the Redhill–Tonbridge line was electrified using the 750 V DC third-rail system.

The scheme was intended to provide a route for freight trains to access the West London Line via Clapham Junction, whilst avoiding the gauge-restricted Sevenoaks Tunnel.

[134] A new timetable was introduced on 4 January 1965, with Class 206 diesel-electric multiple units operating an hourly, all-stations service between Reading and Tonbridge.

As a result of the visible difference in width between the narrow Hastings line stock and the standard-width trailer, the units were nicknamed "Tadpoles".

[2][5] The first goods trains began running on the Redhill–Tonbridge line when it opened in 1842 and facilities for handling freight were provided at Gomshall, Edenbridge and Penshurst in 1844.

[140] The yard at Godstone was equipped with a crane with a lifting capacity of 3 long tons 7 cwt (7,500 lb or 3.4 t)[101] and one of the sidings sloped steeply down to road level, to allow for onward transport of materials.

[55][142][p] Although the South Eastern Railway Act 1836 permitted independent operators to run trains on the line, the SER refused to certify the locomotive that the UMNC had purchased.

[146] Tonbridge West Yard, at the east end of the Redhill–Tonbridge line, was opened in 1941 to facilitate freight traffic movements during the Second World War.

[24] It was extended in the late 1950s to allow the closure of Paddock Wood Marshalling Yard and to relieve freight depots in the London area.

[148] The travelling post office train from Manchester Piccadilly to Dover via Reading, Redhill and Tonbridge was routed along the line from May 1988[149] until 1996, when a new road and rail postal hub opened at Willesden.

[150] Despite the electrification scheme of the mid-1990s, dual-voltage Class 92 locomotives, specifically designed to haul freight and overnight passenger trains via the Channel Tunnel, cannot be used on the Redhill–Tonbridge line owing to incompatibility with the signalling system.

[5][151] The Network Rail 2008 Strategic Business Plan recommended an enhancement project to enable international freight traffic to use the line.

[158] It also reported that a programme to improve weather resilience was planned, which would reduce the likelihood of line closures caused by landslips.

[163] The report concluded by stating that current rail links between Kent and Gatwick are not attractive and that any future service enhancements are dependent on the development of a full business case, which might require subsidy to cover increased staff and rolling stock costs.