Will the Northern Line be extended to arrive at Clapham Junction? The project moved a step closer last November when Wandsworth Council received the response to their commissioned report. According to the findings, there were ‘no engineering or geological constraints’ preventing the extension.
According to ianVisits’ website this was not a surprise as the complexities of tunnelling through London are now quite well understood. The site commented that “if such an extension were to be built, the tunnels would likely run westwards underneath the edge of Battersea Park, then turn southwards to pass under Falcon Park to arrive at Clapham Junction.” The main constraints would be the location of ventilation and access shafts, and most crucially, how and where to build a Northern line terminus station at Clapham Junction.
The Council now plans to consult the local population this year to gauge support for the extension.
Labour councillor Jenny Yates, Cabinet Member for Transport, said:
“We completed a feasibility study into extending the Northern line to Clapham Junction, and the findings will factor into any long-term plans for the area.We want to hear the views of all the people who live, work or visit this part of the borough so that any future plans reflect local community needs and contribute to growth.”
Back in February 2023, Wandsworth Transport Committee commissioned a feasibility study “to explore options to progress feasibility work on the potential for extension of the Northern Line to Clapham Junction.”
The Council launched an 18-month Clapham Junction Masterplan project in March 2024, comprising two phases: an interchange link for the station and potential development around the station. However, as noted during the February 2023 Transport Committee:
“It was important to understand what land might be needed for any Crossrail 2 or Northern Line Official extension as this would be key information to be aware of, before any masterplan for the area was worked on.”
Recognising that many local residents support the idea, local politicians have consistently expressed their commitment to lobbying in favour of the extension. Last June, Marsha de Cordova, our current Battersea MP, reiterated her support in the interview published on CJI, saying:
“As part of the redevelopment plans, I want to see the Northern Line extended to Clapham Junction – imagine the investment and opportunity that it will bring to our community!”
However, the absence of “physical restrictions” doesn’t guarantee feasibility. When questioned in 2021 about why the extension stopped at Battersea Power Station, the Evening Standard reported an official explanation:
“On investigation, I was told this was deliberate (aside from the need to save costs): the number of passengers who would have joined at Clapham [Junction – sic!] would have overloaded the Northern line and meant no space for those waiting to board at Battersea Power Station and Nine Elms.”
In essence, the concern was that regular London commuters would have filled the trains, leaving less space for residents of the new luxury developments in Nine Elms, which comprise about 90% of all new constructions.
No funding for such project
Although local politicians have always committed to lobby TfL for the Northern Line to reach Clapham Junction station, many see this ambition as wishful thinking for one main reason: there is currently no funding for such a significant infrastructure project.
When the Northern Line was extended to include a branch stopping at Nine Elms, many questioned why the 3km project between Kennington and Battersea Power Station didn’t continue an additional 3km to reach Clapham Junction—the heart of Battersea—where it would benefit existing local residents.
However, the response was quite obvious: money! It is worth remembering that the extension to Nine Elms and Battersea Power Station was financed by developers’ money and used as an incentive to enhance the attractiveness of the new quarter, providing investors with a guarantee that it would be connected to the Tube.
In 2010, during George Osborne’s austerity measures, City Hall, under Mayor Boris Johnson, announced that the Northern Line Extension (NLE) would rely heavily on private funding. Developers were expected to contribute approximately £560 million of the £1 billion budget.
The NLE, completed in 2021, cost around £1.1 billion. The funding was split between business rates (70%) and local developer contributions (30%), collected through Section 106 agreements and the Community Infrastructure Levy (CIL) by Wandsworth and Lambeth councils. Notably, the £700m contribution was actually a loan from the GLA, to be repaid within 20 years through business rates collection.
To secure the Northern Line contribution from property developers, Edward Lister, former leader of Wandsworth Council and then deputy Mayor of London, agreed to reduce the requirement for affordable housing in the new developments. Effectively, funds that should have provided affordable homes were redirected by Wandsworth to infrastructure that would primarily increase the value of the private developments.
In December 2024, a question raised by the Battersea MP prompted Simon Lightwood, the Under-Secretary for Transport, to respond:
“We recently provided £485m in funding to support Transport for London’s (TfL) capital programme for 2025/26 and will continue to work with TfL to understand its capital funding needs, which will be considered at Phase 2 of the Spending Review. However, transport in London is devolved to the Mayor of London and TfL and it is for the Mayor to assess the merits of capital projects and make decisions on investment.”
The £485m mentioned is likely to be only half the amount needed for the extension. Moreover, TfL’s response in November 2024 didn’t provide concrete answers; it simply confirmed that there were no engineering or geological barriers to the project, not saying that it could go ahead in term if infrastructure and funding. This had already been acknowledged when Wandsworth Council commissioned the feasibility study, stating:
“It was agreed that the overhaul of Clapham Junction would have a significant financial cost, and the Committee asked whether developer contributions would be used to contribute towards the final cost, or if other financial contributors were planned. The response was that it was too early at the current stage for this to be considered, as the current work was towards the initial feasibility planning of whether an extension was possible with appropriate engineering works.”
It is interesting to see that during that meeting in February 2023, Conservative councillor Daniel Hamilton, member of the Transport Committee, expressed cautious on the media coverage of the study, commenting:
“the report might generate unrealistic expectations amongst the press and public which would lead to a belief that a Northern Line extension was all-but confirmed.”
In 2023, WBC’s Director of Environment and Community Services, Paul Chadwick, said:
“The exact cost of such an extension and how it would be funded are not yet known, but [it] is likely that the further extension would cost significantly more than £750m.”
If the same approach as the Nine Elms extension is adopted, private developers would need to provide significant funding. This could mean large-scale redevelopment, including high-rise buildings at Clapham Junction. The Greater London Authority (GLA) has suggested the area could accommodate 2,500 new homes and 2,500 additional jobs. However, considering the backlash against the proposed 42-storey twin towers project in 2008, one might question whether such plans align with local residents’ preferences.
And if the same approach as for the Nine Elms extension is to be considered, money will have to come from private developers, which also mean a massive redevelopment with high rise building of Clapham Junction (the Greater London Authority (GLA) is actually advocating the idea as it released a plan which says the Clapham Junction area could accommodate 2,500 new homes and 2,500 extra jobs).
However, considering the backlash against the proposed 42-storey twin towers project in 2008, one might question whether such plans align with local residents’ preferences.
In addition, there are also currently discussion (on hold due to lack of funding!) regarding the Northern Line split, especially towards Camden branches. And of course, there’s Crossrail 2. While Crossrail 2 has not been abandoned, the high cost of completing the Elizabeth Line has placed it on indefinite pause. TfL’s resources may not be sufficient to accommodate all these potential expansions.
Overground link implemented in 2012
The last time that Clapham Junction had a new connection added, was with the overground link implemented in 2012, which made the name “Clapham Junction” appear for the first time on the official London Tube map.
The project involved a 2.5 km (1.5 mi) link from south of Surrey Quays to the Network Rail South London Line, utilising a disused alignment previously used by trains from Rotherhithe to Peckham until 1911.
A key asset of the project was its relatively low cost (£75 million) compared to Phase 1 (£1.2 billion) and the Jubilee Line extension (£3.5 billion).
Additionally, the extension passed near Brixton Tube station without a connection to the Victoria line, leading to criticism over missed integration opportunities.
Upon opening, the extension provided four trains per hour between Clapham Junction and Dalston Junction or Highbury & Islington, enhancing connectivity for South London residents.
- Read our article: Clapham Junction station to welcome the East London line in 2012
As of December 2023, the service operates as part of the London Overground’s Windrush line, offering improved transport links and encouraging local investment. However, despite its 17 platforms and the Overground, there is still no Underground Tube connecting Clapham Junction.
Although the 2024 report stated there are no “engineering or geological restrictions” to extending the Northern Line, much more is required to turn the aspiration into reality. Articles like Time Out’s optimistic take—“Soon, getting to brunch dates at Brickwood and nights out at Infernos… could become a lot easier”—might be overly utopian. However, keeping the idea alive maintains hope for its eventual realisation.
For now, the prospect of extending the Northern Line to Clapham Junction remains an intriguing vision, but one constrained by practical challenges, funding limitations, and community concerns. A more realistic prospect, however, is the Crossrail 2 project, which would not only serve Clapham Junction but also significantly improve the connection between north and south London.
