Rectifications led to a restricted loading gauge along the line, requiring the use of dedicated rolling stock.

Served by steam locomotives from opening until the late 1950s, passenger services were then taken over by a fleet of diesel-electric multiple units built to the line's loading gauge.

[14] The SER was granted permission to build a line from Ashford in Kent to St Leonards, East Sussex in 1845.

The SER sought permission to extend their branch from Tunbridge Wells across the High Weald to reach Hastings.

The SER was anxious to construct the line as economically as possible, since it was in competition with the LBSC to obtain entry into Hastings and was not in a strong financial position in the mid-1840s.

All tunnels had been completed and a single line of railway had been laid for a distance of 10 miles 40 chains (10.50 mi; 16.90 km) from Tunbridge Wells.

[22] Grove Hill Tunnel had been built with just a single ring of bricks and no filling above the crown of the brickwork.

In order from north to south they are: The original stations on the Tunbridge Wells to Hastings section of the line are mostly in the Gothic or Italianate styles.

[71][Note 5] In 1882, an 18-mile-40-chain (18.50 mi; 29.77 km) long railway was proposed from Ticehurst Road to Langney, East Sussex, giving access to Eastbourne.

The scheme was deferred, with another proposal in 1937 costing £1,300,000 also failing to gain favour before World War II broke out.

[74] In October 1946, the Southern Railway announced a programme to electrify all lines in Kent and East Sussex in three stages.

[1] In 1899, the SER and LCDR entered into a joint working partnership, the South Eastern and Chatham Railway (SECR).

The train, consisting of the Royal Saloon, two first class carriages and a brake van made the journey from Bricklayers Arms to Tunbridge Wells in 75 minutes.

[91] As built, it was envisaged that the West Country and Battle of Britain class locomotives would be able to work the line.

Forty-eight locomotives of the West Country and 22 of the Battle of Britain class were built with cabs that were 8 feet 6 inches (2.59 m) wide and paired with tenders of the same width.

Diesel-electric multiple units of what became British Rail Class 201, 202 and 203 (the "Hastings Diesels") took over working the route.

Freight trains from Tonbridge West Yard were not permitted to depart until the line was clear as far as Southborough Viaduct.

[104] Special narrow bodied diesel electric multiple units were introduced in 1957–58 to replace steam traction.

They were delivered in six-car formations (the 6Bs including a buffet car) and two units were often operated in multiple to form twelve-car trains.

[91] The Hastings Diesels also worked services on the Bexhill West branch line until closure on 14 June 1964.

These enabled the last steam workings, overnight newspaper trains, to be withdrawn from the Hastings line.

The vehicle was ballasted so that it leant away from the tunnel walls by some 3 inches (80 mm) and was worked to Robertsbridge at a maximum of 20 miles per hour (32 km/h).

Reasons that decided the issue included a commitment by British Rail to eliminate asbestos from all stock in service by 1988 and the increasing cost of maintaining the then ageing Hastings Diesels.

Electrification was finally completed in 1986, the line was electrified using 750 V DC third rail using standard rolling stock, and the expedient of singling the track through the narrow tunnels.

The track in Grove Hill Tunnel was relaid on a concrete base, allowing alignment to be precisely controlled.

The first passenger carrying train comprising C1 stock to use the line was a railtour on 15 March hauled by 50 025 Invincible.

Those departing at xx:15 called at Waterloo East, Sevenoaks, Tonbridge, High Brooms, Tunbridge Wells, Wadhurst, Battle, St Leonards Warrior Square and Hastings, taking 84 minutes.

Those departing at xx:45 called at Waterloo East, London Bridge, Orpington, Sevenoaks, Hildenborough, Tonbridge and then all stations to Hastings, taking 99 minutes.

[120] Class 508 electric multiple units also operated services on the line from the Redhill direction as far as Tunbridge Wells.

[96] The line retains all its original intermediate station buildings, and is considered a well-preserved example of a Victorian secondary rail route.