The Mid-Kent line was built by the Mid-Kent and North Kent Junction Railway (MK&NKJR) and was opened on 1 January 1857 as far as Beckenham Junction (although it was not technically a junction as the West End of London and Crystal Palace Railway's line did not open until 3 May 1858). From opening the line was worked by the South Eastern Railway (SER). Seven years later the MK&NKJR built an extension from a new junction station at New Beckenham to Croydon (Addiscombe Road) which again was operated by the SER.
