The Great Northern route is formed of the Northern City Line, Hertford Loop line, the southern section of the East Coast Main Line between London Kings Cross and Peterborough, the Cambridge line, and the Fen line. Since Greater Anglia withdrew its services to King's Lynn in May 2023, Govia Thameslink Railway became the sole operator of the entire route except between London Kings Cross and Peterborough, and between Cambridge and Ely. The route serves 55 stations.
The term Great Northern is related to the Great Northern Railway (GNR), the original builders of the line.
London King's Cross to Cambridge - Six stopping and two (three on Saturday) semi-fast services from Monday to Saturday, one northbound and two southbound stopping services on Sunday. The fastest service took about 1 hour 30 minutes.
London King's Cross to Royston - Two (three on Wednesday) additional services from Monday to Saturday, one additional service on Sunday.
London King's Cross to Baldock - Seven additional services from Monday to Saturday.
London King's Cross to Letchworth - Three additional services from Monday to Saturday. The last service on Wednesday ran past midnight into Thursday morning.
British Rail
Since the 1960s, the term Great Northern has been used to describe the suburban part of the East Coast Main Line and its branches, rather than the original extent of the GNR. The GNR had proposed electrification of part of the line in 1903, but it was not until 1971 that a scheme to electrify the line from London King's Cross and Moorgate was authorised. Electrification reached Welwyn Garden City and Hertford North on 3 November 1976, with EMU services starting on 8 November. The previous weekend, services over the non-electrified route to Broad Street and Farringdon were withdrawn. The first electric units used for suburban services were Class 313s, followed by Class 312 in February 1978. From that point, the route was promoted as Great Northern Electrics.
The Cambridge Line was chosen for electrification in 1978, primarily because it allowed an alternative electrified route to London while essential upgrade works were carried out on the West Anglia Main Line. However, electrification was not pursued further than Royston as it was not considered value-for-money to electrify as far as Cambridge. This meant that the through service was severed, and passengers had to change from the electrified service at Royston to a diesel train service to Cambridge. On 4 March 1987, approval was given by Network SouthEast for the extension of electrification as far as Cambridge; electric operation commenced on 16 May 1988.
With the further electrification of the East Coast Main Line between 1986 and 1988, electric services could be extended to Peterborough and the outer suburban service was changed from Class 312 to Class 317, some of which were cascaded from the newly created Thameslink route, with the remainder newly built.
In the late 1980s, introduction of new driver-only operation (DOO) services on the route were hindered by ongoing industrial disputes between British Rail, ASLEF, and the National Union of Railwaymen. These services were originally planned to coincide with the upgrades to the line, and were planned for September 1985 notwithstanding union intervention, which occurred when signallers at King's Cross who demanded increased pay. DOO disputes were eventually solved nationally in 1987 and 1988, when new pay rates and career paths for affected staff were agreed respectively.
Privatisation
At privatisation the services became part of West Anglia Great Northern, becoming their sole route in 2004 when the West Anglia services were transferred to 'one'. In April 2006 the services became the responsibility of First Capital Connect. In September 2014, the Department for Transport transferred the new Thameslink, Southern and Great Northern franchise to Govia Thameslink Railway. Passenger services on the Great Northern route, along with all others operated by Govia Thameslink Railway, transferred to Greater Thameslink Railway on 31 May 2026.
In 2006, the Office of Rail and Road released a document entitled Issues in Defining and Measuring Railway Capacity, in which they discussed various capacity issues on the East Coast Main Line and projects aiming to mitigate them. Commenting on the idea of a flyover at Hitchin, they argued such a project "would undoubtedly make pathing more flexible and operations more robust"; however, they also said that it would not increase capacity as it was Digswell Viaduct that was the limiting factor on the number of services ran.
The subsequent construction of the Hitchin Flyover came about as part of a £47 million package into East Coast Main Line improvement work to reduce delays and increase capacity. Network Rail predicted that the flyover would decrease delays by 30,000 minutes/year. The plan for the flyover was set out in the Network Rail (Hitchin (Cambridge Junction)) Order 2011 (SI 2011/1072), which was a statutory instrument permitting its construction by Network Rail. It was published on 31 March and came into force on 21 April. In November 2011, the Department for Transport listed the flyover as an 'existing infrastructure project' in its annual National Infrastructure Plan. Construction was completed in June 2013. In order to minimise disruption to the East Coast Main Line, the viaduct section was installed during night-time possessions of the railway, before installing crash decking which allowed work on the viaduct to continue during the day when the line below was active.
A station to the south of Cambridge was first proposed in 2017, and although its application to New Stations Fund 2 that year was unsuccessful, the November 2017 budget allocated it £5 million in funding. The station, called Cambridge South, is situated between Foxton and Cambridge on the Cambridge line, serving the Cambridge Biomedical Campus and the wider Trumpington area. The station was opened in June 2026, which is a delay from the originally proposed date of late 2025. The station is managed by Greater Anglia and is served by all Greater Anglia, Great Northern, Thameslink and CrossCountry services passing through the station. Additionally, East West Rail services will also call at Cambridge South in the future, once East West Rail has been built to Cambridge and opened.
Network Rail (Hitchin (Cambridge Junction)) Order 2011
The majority of Great Northern services are operated with Class 379Electrostar units. On 12 March 2024 it was announced that Great Northern would lease 30 Class 379 units from Porterbrook. These were introduced for their services to Letchworth Garden City in February 2025, which replaced Class 387 units in order to allow them to be transferred to Southern.
The route of East West Rail, the new railway linking the cities of Oxford and Cambridge, will intersect with the East Coast Main Line at Tempsford in Bedfordshire, where a new station will be built to serve both routes. This has led to worry from local residents, particularly due to a report by East West Rail that the population of the village could grow from 600 to 44,000. As a result of extra funding in the 2024 budget, East West Rail will deliver the station five years earlier than planned, allowing passengers on the East Coast Main Line to access the station before it opens as part of the East West Rail route.
Both Cambridge South and Cambridge stations on the Cambridge line will also be served by East West Rail, the Bedford–Cambridge section of which is in consultation as of 2025. The current plan for the route will include a grade-separated junction with the line at Hauxton, between Foxton and Cambridge. This will include improvements to Hauxton level crossing. East West Rail confirmed in their 2021 consultation that the Cambridge line will remain double-tracked between this junction and Shepreth Junction, where the line will be quadrupled to run alongside the West Anglia Main Line as far as Cambridge.
The last refresh of the lineside signalling system on the southern ECML between London King's Cross and the Stoke Tunnel was commissioned in 1977 and as such was up for renewal between 2020 and 2029. Instead of renewing the current lineside signalling, it was decided to upgrade this section of the ECML to ERTMS in-cab signalling. This will not be the first instance of ERTMS on the UK rail network; it is in use on the Cambrian Line (where it was first piloted), on the Thameslink core Widened Lines route (with an ATO overlay), and on the Heathrow branch of the Great Western Main Line. However, it is the most complex application yet; it is the first use in the UK of ERTMS on such a busy, mixed-traffic line, with freight, commuter, regional and inter-city services sharing as few as two tracks in the tightest sections.
Unlike the Widened Lines route and the GWML, where ERTMS complements traditional lineside signals, the southern ECML will have its signals removed once the transition period to ERTMS is complete. This means that all trains running on the route will be required to be fitted with the appropriate onboard equipment.
The Class 800 series (LNER Azuma Classes 800 and 801, Hull Trains Paragon Class 802, Lumo Class 803), Thameslink Class 700 and Great Northern Class 717 fleets are fitted with ERTMS equipment from manufacture. The Great Northern Class 387 fleet is undergoing retrofit, with the first train sent to Worksop Depot in October 2022. Following its return to service in July 2023, the remaining trains will be retrofitted in Hornsey Depot. The introduction of in-cab signalling will allow the ECML line speed to be increased to 140mph in some places. The Class 800 series trains were designed to reach this speed, but minor modifications will be required to remove the equipment that is currently limiting speeds to 125mph. There are currently no plans to retrofit ERTMS equipment to the InterCity 225 fleet, as they are expected to be withdrawn before the removal of the lineside signals; this means they will never reach their design speed of 140mph (225km/h) in service.
Works to commission new ETCS digital signalling on the line, along with the first test train under the new system, took place during the Early May Bank Holiday in 2022. The new signalling system was approved by the Office of Rail and Road in March 2023, and gradually introduced on passenger services from 27 November 2023. By November 2024, all passenger services were operated under ETCS signalling, with traditional lineside signals completely removed on 18 May 2025.
Network Rail used Beacon Rail owned Class 313 unit 313121 as a test vehicle for ERTMS on the Hertford Loop line. The plan involved resignalling a 5+1⁄2-mile (8.9km) section of the double track route to allow existing passenger and freight services to work bi-directionally over the up Hertford Loop line, freeing the down line for ERTMS tests and evaluation.
TfL takeover
On 20 September 2025, Transport for London (TfL) submitted an outline business case to take over Great Northern services from Moorgate to Welwyn Garden City, Hertford North, and Stevenage and integrate it into the London Overground network. TfL wants to increase the number of trains from two trains per hour to four trains per hour, standardise fares across the route, serve a 21,000 home development at Crews Hill, and boost growth in North London and Hertfordshire. The takeover could occur in Autumn 2027, after Govia Thameslink Railway's franchise ends, if approval is given by DfT; however, the Overground services would use the existing Class 717 stock.
↑Bradshaw's July 1922 Railway Guide. Manchester: Henry Blacklock & Company. 1922.
123Phillips, Charles (2025). The Great Eastern Railway – From the Grouping to the Elizabeth Line 1923–2023. Pen and Sword Transport. p.161. ISBN978-1036103606.
12Gladwin, Tom; Neville, Peter; White, Douglas (1986). Welwyn's Railways: A History of the Great Northern Line from 1850 to 1986. Castlemead Publications. pp.55, 89. ISBN978-0948555046.
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