York Historic Environment Record

The monument includes earthwork and buried remains of a World War II bombing decoy site. It is located on an area of unimproved wetland known as Heslington Tillmire lying to the south of York. The site was established in order to divert enemy bombers from attacking the City of York. The monument was one of a series of decoy sites established to protect 22 historic towns throughout the country which were under threat from what were known as the Baedeker Raids. York was targeted by one such raid on the 29th April 1942 when 79 heavy high explosive and several thousand incendiary bombs were dropped on the city resulting in the deaths of 94 civilian casualties and a number of service personnel. Consequently a decoy site was established. The first reference to this was in a list dated 12th May 1942 and the site became operational on the 15th May. It consisted of 40 large baskets of inflammable material, electronically fired from a remote location. The last reference to the site is 19th December 1942. It is known that some of the baskets were ignited for test purposes but there is currently no record of the site having been lit for operational purposes. The site was under the control of No 4 Bomber Group based at York. It was sited at this location partly because it was wet ground and thus did not use up valuable agricultural land needed to provide food as part of the domestic war effort. The decoy site was a temporary version of what was known as the Starfish type of decoy. This simulated different types of bomb damage by igniting different types of fire in separate areas each defined by a firebreak trench excavated around it. The firebreaks, which enclosed the fires, survive as clearly identifiable earthworks. They take the form of shallow ditches measuring up to 1.75m wide and 0.75m deep, describing irregular shaped enclosures. There are seven such enclosures spread throughout the area of the monument and they are between 50m and 175m apart. The enclosures range in size from 50m by 40m to 25m by 20m. In some cases there is a slight bank on the inner side of the ditches. The area between the enclosures will contain evidence for the construction and maintenance of the whole site such as access roads, lightening conductors to prevent accidental firing and cable ducts. It is known that such roads were often camouflaged with soil and turf and thus may survive as buried features. The decoys were operated from a small brick building believed to be located at NGR SE63904790. This building has been demolished and no longer survives and is thus not included in the monument. World War II 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 c.1000 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 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 mostly located in southern and eastern England. 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, 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. All sites with significant surviving remains will be considered of national importance, as will those where a well-preserved night shelter has been identified. The remains of the firebreaks at Heslington Tillmire survive well and evidence of their construction and use will be preserved. Important information about the layout and operational functions of the complex as a whole will be also preserved within and around the firebreaks.