Exploring Kent's Past

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Monument details

Summary

The site of a Second World War QF P-series oil bombing decoy at Allhallows on the Hoo Peninsula, dating from 1940-41. Used to deflect wartime bombing raids from extensive oil storage installations located 2km to the south, on the Isle of Grain.

Monument Types

• BOMBING DECOY SITE (Modern - 1940 AD? to 1945 AD)

Full description

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QF type night bombing decoy site for unknown site in Chatham area. Extensive remains, including control bunker and support for fire pit.
Owner : Private
Publicly accessible : Yes
How accessed for survey : Public footpath immediately adjacent.
Tourism Potential : Possibly part of Thames side Heritage Trail.
Condition : very good
Date of visit : 07/08/22

(1 and 2).

National List entry Description

Summary of Monument:
The site of a Second World War QF P-series oil bombing decoy at Allhallows on the Hoo Peninsula, dating from 1940-41. Used to deflect wartime bombing raids from extensive oil storage installations located 2km to the south, on the Isle of Grain.

Reasons for Designation:
The site of the Second World War QF P-series oil bombing decoy at Allhallows is scheduled for the following principal reasons:

* Period: as one of eleven specialised QF (controlled fires) P-series (Petroleum Division) oil bombing decoy sites developed between 1940 and 1941 to deflect wartime bombing raids from extensive oil storage depots during the Second World War;

* Rarity: as a rare example of a near-complete OF P-series oil bombing decoy, one of only two of this type known to survive in England;

* Survival and diversity: a well-preserved, extant and fully legible bombing decoy of an unusual type, with all of its principal decoy features surviving above and below ground, including its control buildings;

* Documentation: the site is well-documented having been subject to research and aerial photographic survey, the bombing decoy is included on historic OS maps and records;

* Potential: there is a high potential for further archaeological remains associated with the oil pools, connecting channels and other principal decoy features. There is also potential for artefactual and waterlogged ecofactual remains.

History:
The Second World War saw the emergence of aerial bombardment as a decisive instrument of warfare, and to counter this threat, the United Kingdom maintained a flexible and diverse mechanism of air defence throughout the war. This included the early warning of approaching aircraft, through radar and visual detection, and the local defence of towns, cities and other vulnerable points using anti-aircraft gunnery and balloon barrages. But less conspicuously, many potential targets were shadowed by decoys - dummy structures, lighting displays and fires - designed to draw enemy bombs from the intended points of attack. Britain's decoy programme began in January 1940 and developed into a complex deception strategy, using four main methods: day and night dummy aerodromes ('K' and 'Q' sites); diversionary fires ('QF' sites and 'Starfish'); simulated urban lighting ('QL' sites); and dummy factories and buildings. In all, some 839 decoys are recorded for England in official records, built on 602 sites (some sites containing decoys of more than one type). This makes up the greater proportion of the c1000 decoys recorded for the United Kingdom. The programme represented a large investment of time and resources. Apart from construction costs, several thousand men were employed in operating decoys, the fortunes of which were closely tied to the wartime targets they served. The decoys were often successful, drawing many attacks otherwise destined for towns, cities and aerodromes. They saved many lives.

Urban decoy fires were known as 'SF', 'Special Fires' and 'Starfish', to distinguish them from the smaller 'QF' installations. Each town was protected by a cluster of these decoys, the most technically sophisticated of all the types, with each Starfish replicating the fire effects an enemy aircrew would expect to see when their target had been successfully set alight. The decoys included variation in fire type, duration of burning and speed of ignition. In a permanent Starfish decoy all fire types were used, set in discrete areas defined by firebreak trenches and controlled from a remote shelter. The whole array was linked by a network of metalled access roads. 'Temporary Starfish' (all built in 1942 to counter the threat from the so-called Baedeker raids against historic towns and cities) only had basket fires. In all, 228 decoys with a Starfish component are recorded in England, 37 of which were 'Temporary Starfish', and the rest 'Permanent'. The Permanent sites were located mostly in central England, close to the urban and industrial targets they were intended to protect; temporary sites, like the Baedeker targets they were protecting, were confined to the south and east.

QF sites were first provided for the night protection of RAF airfields, but from August 1941 their role was extended to protect urban centres. Although similar to Starfish decoys, they differed in being considerably smaller, using a limited range of fire types and being sited for the local protection of specific vulnerable points rather than whole cities or conurbations. These new QF sites of 1941-2 fell into four groups, for the protection of: urban and industrial targets (the 'Civil Series', located mostly in the west Midlands, north-west and in the Middlesbrough area); Royal Navy sites (these were few in number and sited to protect coastal bases); Army sites, to protect ordnance factories or military installations (these existed in a sparse belt running from central southern England into the west Midlands); and oil installations and tank farms (the 'Oil QF' sites). In all, only about 100 QF sites were operational in England. Very little now survives of any of these decoys, most having been cleared after the war.

The Second World War QF P-Series oil bombing decoy at Allhallows was identified during Historic England’s Hoo Peninsula Historic Landscape Project (Carpenter et al, 2013). This led to a further programme of archaeological work on the bombing decoy itself comprising historical research to place the decoy in its national context combined with aerial photographic assessment of its surviving remains (Small, 2014). The surviving elements of the decoy site are visible on the first available aerial photograph of the site taken in 1946. Recent aerial photographs on Google Earth taken in September 2013 and by Historic England during a reconnaissance flight in March 2014 confirm all the main structures of the decoy including oil pools and associated structures and the remote control buildings are still extant. The site is documented in Air Ministry records as QF decoy P.1 (Allhallows (Grain)) and is one of eleven specialised oil QF sites completed between 1940 and 1941. Only two are known to survive – the Allhallows site and Shell Haven, Fobbing in Essex (a scheduled monument; National Heritage List for England 1020489).

The Allhallows site was constructed to deflect bombing away from the extensive oil storage depots 2km to the south on the Isle of Grain. It was operated by the Petroleum Board (hence 'P-series') until 1943 when its control transferred to the naval authorities. These decoys were designed to burn large quantities of fuel oil in a variety of brick or clay lined pools and channels shaped to simulate burning oil fuel storage tanks and installations targeted by bombs when seen from the air (Small, op cit). Typically each site included three basic types of pool: a circular oil 'ring', a crescent, and an irregular elongated pool or channel. The oil rings and crescents were constructed from a double skin of bricks packed with creosote-soaked wood shavings fed with oil through a system of buried pipes and valves from a storage tank. The levels of oil were kept level through a network of balancing lines. Fire clay linings were used early on, but may have been replaced at a later stage. Additional Starfish-type boiling oil fire installations were linked to the outside of the oil ring (Dobinson, 1996, 62). The site was manned and controlled remotely using electrical ignition from a sheltered control building some distance away (Dobinson 2000, 147, 149).

Details:

PRINCIPAL ELEMENTS The monument includes a complete QF P-series oil bombing decoy site in two separate areas of protection, which comprises the below ground structural remains of two circular oil rings, a pair of mirrored oil crescents, a small irregular shaped oil pool and connecting channels containing balancing lines with concrete sumps and other associated structures, evident as vegetation marks. The principal decoy features are located at TQ 8567 7736 (centre). The remains of two buildings including a reinforced concrete control building and generator building or store, with a surrounding earthwork bank, are located on an area of slightly higher ground, 300m to the west in a separate scheduled area at TQ 8534 7745 and TQ 8531 7748 respectively. The decoy site is situated to the east of Allhallows village on Allhallows Marshes at the eastern end of the Hoo Peninsula, Kent.

DESCRIPTION The decoy site differs slightly from the standard layout for its type and has two circular rings approximately 15m and 20m in diameter, a pair of mirrored oil crescents approximately 20m in length and 5m in width, and a small irregular shaped oil pool, the below-ground concrete structures of which survive. The oil rings are contained within enclosures with a narrow ditch and bank or bund presumably to act as firebreaks. Oil sumps for each pond are located outside the enclosures linked to the pools by channels containing the electrical wires or oil balancing pipes. The outlines of the structures are highlighted by strong vegetation marks on aerial photographs indicating that the oil pool structures are present beneath the turf, their linings intact enough to retain water. The traces of a number of narrow, concrete-lined channels which probably contained the buried balancing lines and possibly the remote ignition wires can still be seen cutting across the site. Some of the piping and wires may survive within these channels. At least one of the external oil sumps for the oil rings at the northern edge of the site can be seen as an open square depression on the northern edge of the site.

The reinforced control building retains its flat roof and projecting blast walls which protected the main doorway. Levelled remains of earthen banks, built to provide additional blast protection extend around the building. Remains of an extant 30m long and less than 1m high narrow earthwork bank are built partly on the old sea wall, immediately north of the reinforced control building. The second building, a generator building or a store survives as a concrete floor with vestiges of the end walls and two parallel inner dividing walls remaining.

EXTENT OF SCHEDULING The scheduling comprises two scheduled areas, the largest of which contains the principal decoy features and is defined by present field drain boundaries to the south, east and west and a modern track to the north which lies within the field boundary. It measures c400m north-south by c400m east-west. The second area, which includes the control buildings, is defined by a field boundary to the west, a track to the south and includes a section of the former sea wall bank to the east which appears to have been used as a protective feature. It measures c75m east-west by c75m north-south. The monument includes a 2m buffer for its support and preservation.

EXCLUSIONS Fences and tracks are excluded from the scheduling although the ground beneath them is included. The surrounding land drains are also excluded from the scheduling (3).

A number of bomb craters are visible on the 1940's aerial photo set held by KCC and avaliable for public viewing on google earth.

A report, undertaken by English Heritage in 2014 details the surviving elements, history and national context of the decoy. Between September 2013 and March 2014 English Heritage conducted a desk-based assessment of the Second World War QF P-series oil decoy that is located in Allhallows Marshes on the Hoo Peninsula. Using aerial surveys and aerial reconnaissance (16th March 2014) the condition of the surviving elements was documented. It is apparent that the surviving structures of the control buildings can be located on the aerial photographs as well as the remaining elements of the decoy structures.

"The rarity and completeness of this site marks the Allhallows oil decoy out as a site of national importance. This also represents a site of local importance to the Hoo Peninsula, the historic home of the naval dockyards and Royal Ordnance depot at Chatham, and three oil storage facilities located at Kingsnorth and Grain." (4)

<1> M J Anderton, 01/01/99, Twentieth Century Military Recording Project, WWII Bombing Decoy Sites (Unpublished document). Ske14468.

<2> MMRG, 08/07/07, Remains of QF Decoy site (Photograph). Ske14541.

<3> Historic England, National Heritage List for England (Index). SKE29372.

<4> English Heritage, 2014, Second World War Oil QF Bombing Decoy Allhallows, Meday, Kent (Bibliographic reference). SKE31433.

Sources and further reading