It was originally part of the South Eastern Railway having been sanctioned by Act of Parliament in 1836 as part of the first railway line from London to Dover. This may explain why the route runs perfectly straight: serving the settlements en route was a secondary consideration. Following the completion of the new South Eastern main line in 1868, along which services run a more direct route between London and Tonbridge, the Redhill–Tonbridge line's function as the trunk route between London and Dover became part of the new line. Aircraft coming into London's Croydon Airport in the early 20th century used this line as a source of navigation. All the stations along this route had their names written in bold white paint on the roof of the station buildings. It starts with an initial curve just outside Redhill where it passes over the Quarry line which is inside the Redhill tunnel. The Bletchingley Tunnel, about southeast of Bletchingley is about long. At the "Crowhurst Spur" connected with the East Grinstead branch of the Oxted line but this was lifted in the early 1970s. Just west of Edenbridge, in a hamlet called Troy Town it crosses, but does not connect with, the Uckfield branch of the Oxted line. The line was electrified with 750 V DCthird rail in 1993 and services started to run through to London rather than being an extension of the Reading to Redhill North Downs Line service. The electrification also created a diversionary route for domestic services. Stations and services on the line are operated bySouthern using Class 377 units. They provide a service between Tonbridge and London Victoria.
Accidents and incidents
On 28 July 1845, a passenger train was run into by a steam locomotive at, injuring about 30 people.
On 21 January 1846, a bridge over the River Medway collapsed in a flood. The driver of a freight train was killed when he tried to jump clear of the train.
On 1 April 1852, a passenger train was derailed at Edenbridge.
On 22 December 2019, a landslip between Edenbridge and Godstone caused the line to be temporarily closed to traffic. The line reopened and normal services resumed in March 2020.
