Second World War oil 'QF' bombing decoy at Fobbing Marshes (EHER 10328)

A Second World War oil 'QF' bombing decoy situated on Fobbing Marshes, 1.11 km and 1.15 km north west of Oozedam, to the north of the Shell Haven Oil Refinery which occupies a large site on the north bank of the River Thames. A night shelter and oil storage bay of a World War II oil 'QF' decoy which was designed to protect the oil refinery. The decoy would have had many burning pools of oil and simulated ring fires from burning oil storage tanks; these would have been ignited electrically from the night shelter which also housed the generator and decoy manning personnel. The night shelter and the walls of an oil storage facility remain. Documents suggest that it was operational in August 1941 and it may have continued in use until the end of the war. The decoy is one of the original deployment of only two such sites in Essex (the other being 'Thames Haven, Stanford-le-Hope') the purpose of which was to simulate the results of a successful night-time bombing raid on an oil refinery.

Original HER entry merged with NRHE data import: Between the village of Fobbing and Vange Creek, 2.5 kms to the east, is a wide open area of pastureland known as Fobbing Marshes. In the middle, at the furthest point from any road or habitation is what appears to be a WWII decoy bunker. It is smaller, but otherwise of similar pattern, to the decoy at East Mersea (EHER 10036), built of concrete and measuring, generally, 18' x 9'6". The typical sloping entrance - to facilitate earth banking round the outside - leads into two rooms the further of which has steel rungs set into the wall leading up to an observation hatch in the roof. Three steel pipes lead from the south wall of the interior through to the outside. It is not known whether these would have held electricity cables or liquid fuel. There are three ventilation holes high on the walls plus, oddly, two loopholes. There do not appear to be any bolts in the floor for mounting engines or generators. It is known that during WWII Thames Haven Refinery, then perhaps 2 kms to the south-east, was designated a Key Point. This decoy appears to have been constructed in an attempt to draw some of the nighttime bombers away from their target. <1> 50 yards to the west of the bunker stands four 21' long x 4' high concrete walls - each with a 12" gap in the middle. It is not known what these originally were - possibly the remains of storage bays for holding fuel drums. 50 yards to the south of the bunker is a 46" diameter circular concrete chamber set into the ground. It has three pipes leading from it near the top. It is thought to be a cess pit with overflow pipes. Twelve photos of site. <2> <3> Aerial photography from 1981 shows that a control building survives at the site in good condition, but without its earthen covering. <4> The oil 'QF' decoys were built and manned by the Petroleum Board in 1941. Fuel oil was burned in specially-shaped pools and channels lined with bricks or clay. They were ignited electrically from remote shelters. <5> Site Assessment: Beset by development problems and expensive oil usage, only twelve Oil QFs were constructed throughout Britain. It is very possible that the Fobbing site retains the last surviving night shelter of this decoy type. Photographs were taken of the site. <6> - <8> September 1999. Site visit. Documented in contemporary records, "Fobbing" was a World War Two "Oil QF" decoy parented by Shell Haven oil refinery, 2 miles to the SE. QF decoys were an ultimately unsuccessful attempt to simulate the results of a night-time bombing raid on an oil installation. Ignited at the beginning of an attack, burning pools of oil and simulated "ring fires" from burning oil storage tanks would, hopefully, induce following bombers to drop their loads on this position, in open countryside, rather than that of the genuine installation. Control and electrical power for the ignition of the fires came from a substantial earth-covered "night-shelter", situated some distance away, which housed the generator and decoy manning personnel. The contemporary Military Grid Reference of the site, 108/175025, is on open pasture land between Shell Haven and Fobbing. Although nothing survives of the decoy itself, the night shelter and what is thought to be the walls of oil storage bays remain extant in fine condition. The night shelter is built of concrete, is 18' long x 9'6" wide and has a single sloping entrance on its north side. Inside, there are two rooms, which, if this type of night shelter was designed along the same lines as the airfield decoys (see EHER 10107, Nazeing ‘Q’ decoy), would have been the Operations Room and the Engine Room. The Operations Room measures 8'6" x 7'5" and has an escape hatch in the roof at its far end with steel rungs leading up to it. Two steel connection points, which match up with pipework on the outside, were probably the wiring terminals for the electrical ignition of the various decoy devices. Oddly, there are two loopholes in the walls of this chamber. Although providing a means of defence against ground attack, this would have severely limited the amount of earth which could have covered the shelter. The smaller room measures 7'6" x 7'. This probably contained the generator, bolted onto a low concrete base, but the floor of the shelter is covered in rubble and nothing of the base could be seen at the time of the site visit. Fifty yards to the west of the shelter, on heavy concrete foundations, stands four 21' long x 4' high walls, each with a 12" gap in the middle. It is thought that these supported a large steel oil reservoir, necessary for the operation of the site. <9> - <12> July 2002. Scheduling. A Second World War Oil 'QF' bombing decoy situated on Fobbing Marshes, 1.11 km and 1.15 km north west of Oozedam, to the north of the Shell Haven Oil Refinery which occupies a large site on the north bank of the River Thames. A night shelter and oil storage bay of a World War II Oil 'QF' decoy which was designed to protect the oil refinery. The decoy would have had many burning pools of oil and simulated ring fires from burning oil storage tanks; these would have been ignited electrically from the night shelter which also housed the generator and decoy manning personnel. The night shelter and the walls of an oil storage facility remain. Documents suggest that it was operational in August 1941 and it may have continued in use until the end of the war. The decoy is one of the original deployment of only two such sites in Essex (the other being 'Thames Haven, Stanford-le-Hope') the purpose of which was to simulate the results of a successful night-time bombing raid on an oil refinery. <13> August 2013. Site visit. Approximately 80 yards north of the decoy bunker a large concrete block was found, 3' cubed. Concreted into the top of this were two upright metal pipes, 5' high x 3.5 " diameter. Between these uprights, cemented into the top of the block horizontally, were two more pipes, one diagonally across from corner to corner and another beneath this at right-angles. These horizontal pipes have been anchored into the block with wrapped-around steel cables. Studying a photo of the decoy bunker taken in 1994, this showed a pipe, apparently the same, leading from the bunker into the grass. It appears probable that the new discovery was, in fact, part of one of the oil fire arrays which were constructed to simulate the successful bombing and burning of the storage tanks to the south. The pipes would have channelled the fuel to the various decoy arrays. <14> See also: <15>