Investment Programme Report, Quarter 2 2020/21
What it shows. The first public record that our branch was dropped from the modernisation — and it dates the decision to a cost-and-schedule review in September 2020, prompted by pandemic finances. TfL’s own words leave the door open to converting the signalling later. (The same meeting’s Signalling & Controls paper, Item 12 §5.10, separately refers to the “4LM signalling descope areas”.)
“In September 2020, we reviewed the Four Lines Modernisation programme to assess and challenge both cost and schedule. Following this review, the western branches of the District line will not be re-signalled as part of this programme… We will continue to assess whether we can convert this signalling in the future.” Transport for London, Investment Programme Report Q2 2020/21 (11 December 2020)Read the original → (13 MB PDF)
Four Lines Modernisation Programme paper
What it shows. TfL restates the decision and names exactly where the new signalling stops: East Putney (our branch) and Stamford Brook (the Richmond and Ealing Broadway branches). The “continue to assess” wording is repeated word for word. The paper also weighs — and rejects, on cost grounds — giving the Metropolitan line the same treatment.
“…the western branches of the District line will not be re-signalled. This means sections of the District line south of East Putney and west of Stamford Brook will remain under the existing signalling… We will continue to assess whether we can convert this signalling in the future.” Transport for London, Four Lines Modernisation paper (21 July 2021), §4.15Read the original →
FOI-1277-2526 — the branch’s life-expired equipment
What it shows. TfL admits, in writing, that the branch’s train-tracking equipment is life-expired and prone to faults — the root of the daily board errors and delays. (This describes the train-tracking/information layer specifically, not the whole signalling system.)
“…a legacy electronic ‘Train Describer’ system, which includes life-expired equipment. The equipment is prone to faults which means the monitoring of trains can be out of sync or trains are not detected…” Transport for London, FOI-1277-2526 (July 2025)Read the original →
FOI-4657-2526 — where the new signalling stops
What it shows. TfL confirms verbatim that the modern signalling reaches only as far as East Putney, and that the one improvement coming to the branch is better information boards — now due in the second half of 2026, having slipped from an earlier “early 2026”.
“The 4LM project is replacing the signalling system as far as East Putney station.” Transport for London, FOI-4657-2526 (April 2026)Read the original →
Progress with the Four Lines Modernisation project
What it shows. A technical account of the descope: the modern (CBTC) signalling stops at Stamford Brook and East Putney, drivers switch to manual, and the branches keep their existing signalling and trip cocks. The stated reason was framed as conditional — “at the present time”.
“The original intention of providing an overlay system to provide ATO has been viewed as unjustifiable at the present time in view of the lower traffic density and the complications arising from joint running with other operators.” Rail Engineer (May 2023)Read the full article →
“Falls short of full modernisation”
What it shows. The 2026 works are a patch, not a modernisation — track-circuit and monitoring upgrades, not new signalling — and a full overhaul “likely to cost hundreds of millions” remains unfunded. Putney MP Fleur Anderson is pressing TfL, Network Rail and SWR. The article also records the two-day branch fault during the 2025 Wimbledon Championships.
“Changes fall short of full modernisation for Wimbledon branch services.” FulhamSW6 (April 2026), headlineRead the full article →
TfL’s £500,000 fix has failed three times already
What it shows. The interim £500k package failed three times inside a fortnight, and the fault-monitoring switch-on was postponed with no new date. The article also cites TfL’s June 2024 board paper — confirming the branch will not be re-signalled, tracing back to the December 2020 decision.
“TfL’s own board paper, from June 2024, confirms the Wimbledon branch will not be re-signalled… followed a December 2020 recommendation to drop the branch from the Four Lines Modernisation programme.” Putney News (July 2026)Read the full article →
Will the District line branches ever see CBTC?
What it shows. Railway enthusiasts and professionals set out the ripple effect: because nearly every District line train starts from a branch, a fault on the legacy sections can hold up the modernised core. Included for the argument — it’s informed discussion, not a primary source.
“failures can occur on the legacy sections and then block the entire line up” RailUK Forums (September 2025)Read the thread →
More sources
The plain-English explainer footnotes every claim on the site, including the Government primary sources — South Western Railway’s transfer to public ownership (May 2025) and the June 2025 TfL capital funding settlement.
Spotted something we’ve got wrong, or have a document we should add? Get in touch via the campaign page.