Joint Lines of the GER
In common with most railways of a similar size, the GER were part owners in a number of joint lines:
Tottenham and Hampstead Joint
In 1868, in conjunction with the Midland Railway (MR), the Tottenham and Hampstead Joint line was opened. This gave the GER access to other parts of London. This enabled the GER to use St Pancras for some of its services to Cambridge, Ely and Norwich. The service to Cambridge, in particular, was very much in competition with the GNR from their Kings Cross terminus, next door. At the grouping, the use of St Pancras naturally ceased.
Great Northern and Great Eastern Railways Joint (GN&GEJ)
The GER desperately wanted to gain access to the northern coalfields in Derbyshire, Nottinghamshire and Yorkshire because it had to "import" all its own fuel and saw an opportunity for the provision of coal to the London Docks and the carriage of imported goods from the docks northwards. Early attempts to build a line northwards through Lincolnshire failed. After much wrangling with the GNR, a Bill was eventually passed in 1879 which authorised joint ownership of a series of railways from Huntingdon via St Ives, March, Spalding, Sleaford, Lincoln and Gainsborough to Black Carr Junction, Doncaster. Thus the Great Northern and Great Eastern Railways Joint Committee was formed. This missing link between Spalding and Lincoln was opened in 1882 and goods started flowing straight away and soon after a passenger service introduced between London and Doncaster.
Norfolk and Suffolk Joint Railway
In south Lincolnshire number of small independent railways came into being starting in the mid 1850s and continuing through to the 1880s. Both the MR and the GNR took an interest in these and they became an area of conflict between the two companies. In due course, the two railways came to an agreement to form a joint concern and this company took over the various lines in two stages and thus the Midland and Great Northern Joint Railway (M&GNJR) came into being.
At first there was some conflict with the GER over traffic from the Midlands but matters settled down and another line was built with the M&GNJR and the GER as partners and this was known as the Norfolk and Suffolk Joint Railway (N&SJR). This line had two separate sections, Cromer and North Walsham and Yarmouth and Lowestoft. In return, the GER gained some running powers over the M&GNJR.
East London Railway (ELR)
Marc Brunel, assisted by his son, Isambard Kingdom, opened the first tunnel under the River Thames in 1843, this was designed for road and pedestrian traffic. However, it became a disreputable place and a group of railway companies had the idea of turning it into a rail tunnel. The six companies involved were the GER; the London, Brighton and South Coast Railway (LB&SCR); the South Eastern Railway (SER); the London, Chatham and Dover Railway (LC&DR); the Metropolitan Railway (MetR); and the Metropolitan District Railway (MDR). Together, they formed a joint company (ELR) to build the line between Wapping and Rotherhithe. Goods and passenger services between various locations used the line including GER services to south of the river and LB&SCR and SER services into Liverpool Street.
The line eventually became part of the London Tube network and ceased carrying goods in the 1960s. At the time of writing, the line is closed for refurbishment and extension as part of a general expansion of the London commuter train services.
Thank you to Richard Barron for the above information.