Tuesday 16 November 2021

The Black Down Decoy Site (1940-44)

 From January 1940 onwards, an elaborate decoy strategy designed to protect urban areas from aerial bombardment was planned and implemented. Over the course of the next 18 months or so no fewer than 602 such sites were built. There were four types of decoy - dummy aerodromes (K and Q sites), diversionary fires (QF and Starfish), simulated urban lighting (QL sites) and dummy factories and buildings. The QF diversionary site at Black Down is one of the few that wasn't totally eradicated after the end of the Second World War.

Control Bunker - Black Down QF Site

Black Down is the highest point in the Mendip Hills, offering a spectacular view of the Chew Valley. It is close to Cheddar (BS40 7XU / OS Grid: ST 470564) and the QF site can be accessed via a steep path adjacent to Tynings Farm. The site, which formed part of Bristol's defences, operated in tandem with a QL simulated lighting system and Z anti-aircraft rocket battery to the south. The western control bunker is on top of the hill at the end of the steep access path leading up from the farm. It's not possible to get inside but most of the structure is clearly visible, including the blast wall protecting the main entrance.

Tynings Farm and the site of the QL decoy beyond

After a couple of hundred yards beyond the western control bunker (from which both the QF and the QL sites could be triggered) at the top of the access path turn right and walk up towards the trig point on the summit of the hill. The landscape in front of you is punctuated by channels and mounds which, in war time, supported various materials and devices for simulating a city on fire. One can also discern firebreak trenches which enclosed emplacements used for simulating burning building.

Old military road up to the trig point
Simulated Bristol Targets

The planners went to considerable lengths to replicate potential sites in Bristol, the configuration of factories, railways and houses was copied and the site would be lit up on the approach of Luftwaffe bombers, the intention being that they bomb these open spaces in the mistaken belief that they were hitting Bristol. For example Temple Meads was simulated at Point C on the above map. In this instance there was a combination of QL and F features i.e. a lit up area, partially on fire.

Bronze Age Bowl Barrow

At the trig point on Beacon Batch there are a number of Bronze Age burial barrows of which two are particularly prominent (see picture above). From this point look east towards the two masts. The QL site mimicking Bristol's Eastern Depot was situated in that area. There is a second control bunker to the south of this spot on the southern boundary of the Black Down designated site.

500  metres to the south of Tynings Farm there is a bunker with blast wall which was almost certainly the control centre for the Z Battery based in this area. The Z Batteries were manned by Home Guard units and developed from a single-rocket launcher into more sophisticated projectors which could fire a salvo of 36 at the touch of a button. The combination of decoys and ground to air fire power was a potent threat to enemy bomber forces - tricked into releasing their bombs to early, in doing so they were exposed to rocket attack.