The Outer London Defence Ring: Cheshunt, Hertfordshire

During the Second World War, the UK prepared extensive defensive measures to counter a potential German invasion. One of the most significant of these was the Outer London Defence Ring, a fortified stop line encircling the capital. Stretching through key areas on the outskirts of London, this defensive line incorporated a combination of pillboxes, anti-tank blocks, trenches, and minefields to deter and slow down enemy forces. Today, remnants of these defences still exist, serving as a reminder of the country’s wartime resilience.

The Outer London Defence Ring in Cheshunt

Cheshunt, a commuter town on the northern outskirts of London, played a vital role in the Outer London Defence Ring. The surrounding countryside and woodland provided ideal terrain for defensive installations, allowing the construction of a variety of fortifications. The defensive line in this area spanned approximately 4.5km, crossing farmland and woodlands between Wormley West End Woods in the east and Brookfield Farm in the west.

A geodata set held in house by Brimstone shows a range of defensive features along this stretch, including:

• Pillboxes (hardened field defences for infantry and machine gunners)
• Anti-tank blocks (concrete obstacles designed to impede enemy vehicles)
• A lengthy anti-tank ditch (a long, excavated trench to hinder the movement of enemy tanks)
• A minefield (used to inflict damage on enemy troops and vehicles)

Many of these structures remain visible in Cheshunt today, though in varying states of decay. Some pillboxes and anti-tank blocks remain intact, while others have been partially demolished or overgrown by nature.

Key Defensive Structures in Cheshunt

Bread and Cheese Lane Pillboxes and Anti-Tank Defences

Pillboxes were an integral part of the GHQ stop line defences, offering strategic positions for machine gunners and observation posts. In this section of the Outer London Defence Ring, two types of pillboxes were present:

• FW3 Type 27 – A large, octagonal pillbox designed to house riflemen and light machine guns. These were typically built with 30cm thick walls, although shellproof variants with thicker walls were also constructed. The Type 27 is reportedly the second most commonly developed pillbox type, with over 1,300 still in existence today. One example of this can still be found on Bread and Cheese Lane, located next to an anti-tank block.
• FW3 Type 22 – A smaller, hexagonal pillbox typically used for riflemen. A tall version of this pillbox, adapted to allow firing over the crest of the hill on which it is situated, remains on Bread and Cheese Lane. Though in a derelict condition, it is still accessible. It features a sheltered entrance similar to other pillboxes of this type across the UK. During the war, it was reportedly camouflaged to resemble a small residential property. While no traces of this disguise remain, the structure itself is intact, although it has been sealed off to prevent public access.

Adjacent to the FW3 Type 27 pillbox, the anti-tank ditch followed a route immediately north, reinforcing this defensive point. While sections of the ditch have eroded or been filled in over time, traces of its trajectory remain visible, crisscrossing through fields.

Francis Farm and Appleby Street Anti-Tank Blocks

As the defensive line continued beyond Bread and Cheese Lane, it intersected agricultural land near Appleby Street. Here, a series of anti-tank blocks were originally installed to prevent enemy vehicles from advancing. According to historical records, 15 such blocks were placed at this location. Some remain in place, forming a fragmented wall-like structure, while others have been removed over time.

Anti-tank blocks were often used to reinforce weak points in the terrain and were strategically positioned to block key routes, roads and railway lines.

This location on Appleby Street may have been deemed a weak point, potentially due to its low-lying nature, hence the requirement for an anti-tank wall as opposed to blocks. These blocks are located on private land associated with Francis Farm, though they can be viewed from a vantage point in Appleby Park, approximately 140m south of their location.

Appleby Street Farm: A Hidden Minefield

Further east along the defensive line, near Appleby Street Farm, two more Type 27 pillboxes remain. One of these is heavily overgrown and situated within a hedgerow, while the other is easily accessible and has since been repurposed for livestock as a feeding station. Water troughs and hay barrels surround the structure, making it a functional part of the farm today.

Historical data suggests that the field to the north of these pillboxes once contained a minefield. Local Home Guard battalions laid 18 Mk V anti-tank mines in six rows at this location, at the point in which German forces would have likely crossed the anti-tank ditch. The Mk V mine (officially the Anti-Tank Mine, General Service, Mk V) introduced in 1943, was designed to resist blast overpressure and featured a spring-loaded striker. Being primarily composed of steel, these mines were prone to rust, making their activation unpredictable over time.

Although the mines have since been removed, little documentation exists detailing their disposal. Their former presence underscores the level of defensive preparation undertaken during the war. While no live ordnance remains at this specific site, it highlights the risks associated with unexploded ordnance (UXO) in areas with military history.

The Legacy of the Outer London Defence Ring

Though the Outer London Defence Ring was never tested in battle, it serves as a testament to Britain’s wartime efforts to protect its capital. Today, remnants of these defences offer a glimpse into the past, reminding us of the strategic measures implemented to counter the threat of invasion.

For those working in construction or land development, these historical defensive structures pose another consideration – unexploded ordnance (UXO). Many wartime sites are still at risk from UXO, making it crucial to conduct proper risk mitigation before undertaking any groundworks.

UXO Risk Assessments

At Brimstone UXO, we specialise in UXO risk mitigation, ensuring that historical ordnance does not pose a threat to modern-day projects.

A Preliminary UXO Risk Assessment is the most cost-effective and fastest way of determining or discounting UXO risks for your site. With a 24 to 48-hour turnaround, we can determine if your site is deemed low risk, and requires no further UXO risk mitigation support, or if further, more in-depth research is required in the form of a Detailed UXO Risk Assessment.

To learn more about our UXO Risk Assessment service, visit our website or reach out to our Commercial Team.

If you found this article interesting, you may also enjoy:

• The Legacy of the Home Guard: How Their Activities Could Pose a UXO Risk Today
• Operation Sealion: The Invasion That Never Came
• The WWII Blitz on Liverpool Docks: History, Impact, and UXO Risks
• Britain’s WWII Defence Lines

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