It reached an agreement with the London, Brighton and South Coast Railway (LB&SCR) in 1858 to use the Crystal Palace line originally built by the West End of London and Crystal Palace Railway from Beckenham Junction to Clapham Junction to access Battersea and (from 1860) Victoria.

[1][2] On 6 August 1860, the Metropolitan Extensions Act granted the London, Chatham and Dover Railway (LCDR; the successor to the East Kent company) the powers to extend the Chatham Main Line from Beckenham Junction to Battersea and to build a branch line from the Herne Hill to the City of London.

[3][4] After the main extension was built, the City Branch opened on 6 October 1863 from Herne Hill as far as Elephant & Castle, via Camberwell and Walworth Road.

On 1 June 1864, the line had been extended to Blackfriars Bridge railway station (on the south bank of the River Thames) via Borough Road.

[5] Blackfriars Railway Bridge was then built across the Thames and a terminus for trains from the south opened at Ludgate Hill on 1 June 1865[6] (closed 3 March 1929).

[7] Later that year, the LCDR completed work to widen the railway viaduct between Herne Hill and Blackfriars Bridge, which included doubling the number of lines north of Loughborough Junction from two to four.

At the northern end of the bridge St. Paul's station (later renamed Blackfriars) was opened by the London, Chatham and Dover Railway.

Network Rail initially suggested widening the viaduct and demolishing part of the market, but the public backlash against this plan prompted Network Rail to consider permanently routing all Thameslink trains to/from Brighton via Herne Hill, avoiding London Bridge and the market.

[18] This proposal was rejected in 2004 because of its environmental impact on Herne Hill and the larger number of interchanges offered on the London Bridge route; the Borough Market viaduct was widened instead.

[19] During the initial planning in the late 1980s for High Speed 1, British Rail considered building the line to serve a low-level station at King's Cross via south London.

[26] The LCDR was compelled to operate this service by Parliament to compensate for the large number of working-class homes destroyed in Camberwell during the construction of the line.