13 Mobilisation Centres were built between 1889 and 1903 as part of the London Defence Scheme. These were not planned as forts although some of them would have been armed on mobilisation. Their main function was as a store for guns, small arms ammunition, tools and other equipment required for the batteries and infantry allocated for the defence of the neighbourhood in the event of a foreign invasion. The casemates could also be used as barrack accommodation.
The North Weald Redoubt was the first of the mobilisation centres to be constructed and the only fortified centre north of the Thames. It was located on high ground to the south of North Weald Bassett and faced north east with good command of the ground to its front and sides. It was described in 1903 as “situated on a commanding knoll” and that “from mile 17 to 19 the road is commanded by North Weald Fort; a distance about 2 miles east”
Although based on the Twydall profile (an experimental project at Twydall, near Chatham, in which low profile earthwork defences replaced the permanent ditch and rampart defences of a few decades earlier with a resultant low profile), its location was given away by being positioned on a high point. In plan the rampart was roughly semicircular in shape some 500 feet across. In the ditch at the foot of the rampart was an 8 foot high unclimbable or Dacoit steel fence that terminated at each end of the gorge casemates. Behind the rampart, in an arc, were three magazines for cartridges and shells, with shafts to supply the guns above. The flat concrete roof above the magazines was made thicker than that of the adjacent chambers and unusually, not earth covered. No reinforcement to the concrete can be seen so, if the roofs are reinforced, this must be within the thickness of the concrete. All three cartridge stores were entered through shifting lobbies and illuminated by lamps placed in recesses from the adjacent chambers. The lamps for these were kept in a centrally placed lamp room. Between the magazines were two pairs of gun casemates (to shelter the guns in) flanked by two pairs of artillery general stores. It is recorded that doors were never provided to these gun casemates though hinge hooks were fitted to take them.
One cartridge store appears to have had a problem with damp as a gully runs along the rear of the chamber discharging through the wall to the shifting lobby entrance. This opening was covered by a small grill identical to those for the vents to the lamp recesses.
Also here, dividing the above into three blocks, were the entrances to two tunnels that passed through the rampart and emerged in two hollows in its forward. These hollows and others each side of them, formed a discontinuous secondary rampart or ‘fausse-braye’. Manned by riflemen, they would have allowed the parapet to be kept clear for the artillery that the fort was designed to mount. This arrangement was advantageous for the troops manning them as their heads would not be silhouetted against the skyline. So these hollows would not flood in heavy rain, each was provided with a drain. Some thought went into the design of the tunnels, the thickness of the concrete roofs increased in steps towards the outer end, as the thickness of the earth cover above decreased.
At the rear, a dry ditch closed off entry to the site. The ditch scarp was formed by a row of casemates with a parados above.
These casemates were used to store the tools and other equipment to aid construct of the defence position. A pair of doors to one of these casemates, with the inscription “Shell Store No 2' would suggest that shells may have been stored in these gorge casemates. If shells were stored here, they would have been for the external batteries, the shell stores inside the work supplying the guns on the rampart only. To allow easy removal of the contents of the gorge casemates, two ramps entered the longer section of ditch, one at each end. This would have allowed wagons to enter down one, load and exit by the other. When emptied, the casemates were to form a somewhat Spartan accommodation for 72 soldiers.
The ditch was defended by rifle fire from a caponier and loopholes in the steel doors of the gorge casemates. To prevent the caponier being rushed there was a V shaped drop ditch each side of it. Individual smoke vents were provided above the loopholes in the doors, with larger louvered ones serving the caponier.
Entrance to the Redoubt was over the top of the caponier, the roof of it doubling as a road. Two concrete pillars held gates to block passage to the interior in event of attack. The gates were of the same style as the unclimbable fence around the site and contained a wicket gate.
No emplacements were provided for artillery, they would have been dug, on mobilisation, in the six promontories in the rampart. During a bombardment the guns would have been sheltered in the gun casemates until needed. It is not known what the armament of the Redoubt was intended to be, probably, it was not intended for any specific gun, rather it was intended to accommodate any of the likely candidates at the time. In the event it would have been 2O pounder R.B.L. (Rifled breech loader) Armstrong’s (later replaced with 15pounder BL’s), with which the Volunteer Artillery allocated to this position were equipped at the time. A number of factors about the redoubt’s design suggest that four guns would have been emplaced in the central positions with a quick firing or machine gun in each flank position.
Rainwater was collected in six cast-iron cisterns and two concrete tanks, one set into the parados and the other in the counterscarp of the ditch. The total capacity of these was 6217 gallons. To the rear were the caretakers cottages, one contemporary with the Redoubt and the second added three years later, both of different designs. North Weald was unusual in this respect, elsewhere accommodation was provided for two caretakers from the outset in semi detached accommodation.
In 1903/04 shell and cartridge stores holding 7,200 x 4.7-inch shells and cartridges respectively were built at the rear, to the side of the caretakers cottages. These buildings were to provide increased ammunition storage capacity needed when the Volunteer Artillery re-equipped with 4.7 inch and 1 5pounder BL Guns. Rainwater was collected from their roofs in an additional 5,000 gallon underground tank.
There was also an intention to build a tent and blanket store between the cottages and the ammunition stores. Currently there is a much altered building on this site, but it is not clear if this was a later addition.
North Weald was also to have housed the ammunition for the adjacent Kelvedon Hatch sector, which did not have a mobilisation centre of its own.
When the London Defence Scheme was abandoned in 1906, the Redoubt was retained as an ammunition store. In World War I the line of the London Defence Positions was reactivated as the inner stop line to resist a German invasion, though continuing on to Broxbourne rather than stopping at Epping as previously.
The Marconi Co. brought the site and the surrounding land in 1920 and set up the Ongar Radio Station. Control of the site then passed in turn to the Imperial & International Communication Company, Cable & Wireless, the Post Office, British Telecom and, following its sale by British Telecom in 1995, to property developers.
During World War II, because of the importance of the radio station, it was classed as a Vulnerable Point. Special VP Troops were stationed there to protect it and two Allen Williams Turrets were installed, one on each flank. One former cartridge magazine was used as a dressing station, a faded red cross and the words ‘First Aid’ can be made out on the wail of the former shifting lobby.
The Redoubt is a scheduled ancient monument and while surviving remarkably intact down the years thanks to its previous owners, who maintained it to a large degree, the redoubt now stands empty and subject to the attention of vandals, both official and otherwise. Considerable damage has now been done, mainly to the caretakers cottages and external ammunition stores. The ‘dry’ ditch at the rear is now often wet due to a blocked drain, flooding the gorge casemates to their long term detriment.
It was hoped that some restoration would be done, probably as a ‘sweetener’ for the proposed redevelopment of the former radio station site by the new owners. The former radio station buildings were demolished after a fire in 1997 leaving the Redoubt and ancillary buildings standing. A new fences has been installed around the Redoubt but this has already been breeched and the site still open to local vandals and other casual visitors.
- The London Mobilisation Centres by Alec Beanse and Roger Gill published by the Palmerston Forts Society ISBN 0 9523634 5 3