History{{anchor|Great Northern and City Railway Act 1892|Great Northern and City Railway Act 1895|Great Northern and City Railway Act 1897|Great Northern and City Railway Act 1902|Great Northern and City Railway Act 1903|Great Northern and City Railway Act 1904|Great Northern and City Railway Act 1907|Metropolitan Railway Act 1913}}
The
Great Northern & City Railway (GN&CR) was planned to allow electrified trains to run from the
Great Northern Railway (GNR, now the
East Coast Main Line) at
Finsbury Park to the
City of London at
Moorgate. Despite being built using similar methods to the tube network then under construction, the tunnels were built large enough to take a main-line train, with an internal diameter of , compared with those of the
Central London Railway with a diameter less than . For this reason the line was popularly known as the "Big Tube" in its early days. However, the GNR eventually opposed the scheme and cancelled its electrification plans, and the line opened in 1904 with the northern terminus in tunnels underneath Finsbury Park GNR station. It was originally electrified using an unusual fourth-rail system with a
conductor rail outside each running rail. During this period, the line remained an isolated branch, without through services to any other part of the rail network. Carriages were brought to it through a connection into a freight yard near Drayton Park station, where a small depot was built to service trains. The GN&CR generating station closed when the MR took over, and became the studio of
Gainsborough Pictures. After lying derelict for many years, it became a temporary venue for the
Almeida Theatre. The site has since been redeveloped as apartments. After the formation of the
London Passenger Transport Board in 1933, the MR was amalgamated with the other Underground railways and the line was renamed the Northern City Line. In 1934 it was re-branded as part of the Edgware–Morden line (which was renamed the Northern line in 1937), and in 1939 operations were transferred from the Metropolitan to the Northern. As part of London Transport's
New Works Programme, the
Northern Heights plan was to connect the Northern City Line at Finsbury Park to existing main-line suburban branches running to
Alexandra Palace,
High Barnet and
Edgware, which would be taken over by London Transport and electrified. The Highgate branch of the Edgware–Morden line would connect to this network north of Highgate. Only parts of this plan were completed: when the
Second World War started, the Highgate link and electrification of the Barnet branch were well under way and ultimately completed, but the Northern City connection to Highgate was first postponed and finally cancelled after the war. , showing the diversion of the Northern City Line to Alexandra Palace, Bushey Heath and High Barnet. Sections marked in solid green were ultimately taken over. The line from Highgate to Finsbury Park already existed but was to be absorbed by London Transport; this never happened and it closed to passengers in 1954. After being used to transfer tube trains from Highgate depot to the Northern City line, it closed permanently in 1970. After the war there were proposals to extend the Northern City Line north and south. The London Plan Working Party Report of 1949 proposed several new lines and suburban electrification schemes for London, lettered from A to M. The lower-priority routes J and K would have seen the Northern City Line extended to
Woolwich (Route J) and
Crystal Palace (Route K), retaining the "Northern Heights" extensions to Edgware and Alexandra Palace. The lines would have run in small-diameter tube tunnels south from Moorgate to Bank and
London Bridge. The "K" branch would have run under
Peckham to
Peckham Rye, joining the old
Crystal Palace (High Level) branch (which was still open in 1949) near Lordship Lane. Nothing came of these proposals, and the Edgware, Alexandra Palace and Crystal Palace (High Level) branches were all closed to passengers in 1954. As a result, the Northern City Line remained isolated from the rest of the network. In 1964, the Northern City Line (low level) platforms at Finsbury Park were given over to become the southbound platforms of both the Piccadilly line and the new Victoria Line, the former
Piccadilly line platforms becoming the northbound Piccadilly and Victoria lines' platforms. From this time the NCL used Drayton Park as its terminus. At the same time a change was made at
Highbury & Islington, with the northbound Northern City line diverted to a new platform alongside the northbound Victoria line, and the southbound Victoria using the former northbound Northern City platform, both providing
cross-platform interchange. Passengers from Moorgate to Finsbury Park took the Northern City line to Highbury & Islington and then changed onto the Victoria Line. In 1970 the line was connected (as intended by its original promoters) to the mainline via the high level platforms at Finsbury Park as part of a wider plan to electrify ECML suburban services. The line was renamed
Northern line (Highbury Branch) and the following year an agreement was made to transfer it to
British Rail. Commuter trains were run to/from Moorgate instead of
King's Cross, relieving congestion at King's Cross. The last London Underground services ran in October 1975 and British Rail services commenced in August 1976, replacing services to
Broad Street via the
city branch of the
North London Line. These British Rail services used the name "
Great Northern Electrics". The track and tunnels are now owned by Network Rail. Services are provided by
Great Northern to and, via the
Hertford Loop Line, to (with some extending to
Stevenage,
Hitchin or
Letchworth). The name "Northern City Line" has been revived to refer to the underground part of the route. ==Infrastructure==