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.

Friday, 1 October 2021

The Fortified Island of Flat Holm

 From 1870 to 1900 the Severn Estuary was protected by four interlocked forts - Brean Down, Lavernock Point, Steep Holm and Flat Holm. Later, during the Second World War, these sites were redeveloped and brought back into use. Nowadays all of these sites can be visited, and each one is unique and of special interest. Last month I managed to get to Flat Holm Island, the journey itself was a bit of an adventure in that the only way of getting there is in a rib running out of Cardiff Bay.

The Landing Beach - Flat Holm

In Victorian times there were four batteries on the island: Lighthouse, Well, Farmhouse and Castle Rock. Because of the relatively low and exposed terrain the nine 7" Rifled Muzzle Loading (RML) guns deployed on the island, were all mounted on Moncrieff Disappearing Carriages. Many of the guns are still on the island, as they were difficult to salvage, but the carriages are long gone. The sunken gun pits are there to explore as are the tunnels, ammunition stores and the original 1869 barrack block (now a pub, small museum and visitor hub). 

Gun Pit at Lighthouse Battery, Flat Holm

Moncrieff Carriage in Gun Pit

The quarters provided on the island were good for fifty men but generally the island was served by a Master Gunner and five lower ranks. The gun pits were constructed from limestone blocks and bricks - they are 18 ft in diameter and 10 ft deep. When firing their 115-pound shells, the recoil forced the gun into the down position (see illustration above). It was then reloaded and, with the aid of a counter weight, raised ready for firing again. The guns were only fired in tests and in 1888 the R.A. and R.E. Works Committee recommended that a number of the guns be replaced with a 6" breech loading (BL) gun and two 3" quick firing (QF) variants. These upgrades never happened.

The 1869 Barracks & Lighthouse

7" RML Gun at Lighthouse Battery

During what is sometimes referred to as the 'second military occupation' from 1940 to 44, over 350 soldiers were based on Flat Holm. Two anti-aircraft (AA) batteries were established, both consisting of two heavy, 4.5" AA Mark II guns, a command post, and were flanked by two searchlights. Bofor and Lewis guns augmented the AA armament. The batteries were constructed from mid 1941 and throughout 1942 - sometime after the main raids on Cardiff and Bristol between October 1940 and May 1941.

1941 era AA Gun Position - Farmhouse Battery

Searchlight Building and Store - Farmhouse Battery

The pictures of Farmhouse Battery above, illustrate the strategic value of Flat Holm Island. The coastline in the distance is the Weston-super-Mare / Sand Bay stretch of Somerset shoreline, defended by the fort at Brean Down. Steep Holm Island can be seen in the second picture. The main deep water channel up to Bristol and into the Severn Estuary runs between the islands. 

We can garner some idea of what the batteries were like in the wartime years through the work of war artist Ray Howard-Jones (1903-96). After being accredited as an official war artist Penarth based Ray spent several months on Flat Holm and Steep Holm in 1942, leaving a rich legacy of contemporary paintings. The painting below, showing two newly installed A.A. guns is reprinted with the kind permission of the National Museum of Wales and Nicola Howard-Jones. 

Lighthouse Battery under Construction - 1942

Flat Holm became non-operational in December 1944 and in 1945/6 German prisoners of war removed most of the equipment and many of the pre-fabricated structures. Aside from the batteries, ammunition stores, control bunkers and searchlight positions visitors can explore the remains of a G.L. Mk II radar platform and ramp, plus a number of other wartime structures such as the old gas attack store and guard house.

Ramp to G.L. Mk II radar platform

Open Moncrieff Gun at Well Battery

As is the case with Lavernock, Brean Down and Steep Holm it is interesting to see how Victorian fortifications have been reused in later conflicts. The sites chosen in the 1860s and 70s remained relevant in later times and although the gun pits required a radical new approach, some of the other buildings were re-used. The picture immediately above shows an open-backed Moncreiff gun position at Well Battery on Flat Holm, with a 1941 era structure built where the original Victorian artillery piece was originally mounted.

Main References
'A History of Maritime Forts in the Bristol Channel' by J.H.Barrett
'Flat Holm Island: Rich in wildlife, steeped in history' from Cardiff City Council
Bay Island Voyages: https://www.bayislandvoyages.co.uk/