Crymlyn Bog Second World War Barrage Balloon Site

Cadw's description

Summary description and reason for designation

The monument comprises the remains of a Barrage Balloon site which dates from the Second World War (AD 1939-1945). It is located on a low, gently sloping south-east facing spur of land on the western side of, and overlooking, Crymlyn Bog. The barrage balloon site was one of a network of balloons built to act as a form of air defence surrounding the former National Oil Refinery at Llandarcy. Item A consists of the mooring blocks and central anchorage of a T7 type cradle bed used to bed down and fly the balloon from. Set flush into the ground surface, the pre-cast concrete blocks contain embedded metal rings for securing ropes and cables. At the centre, a central anchorage (not visible) is surrounded by a small ring of eight rectangular blocks known as the octagon. Radiating out beyond this octagon circle are the remains of the 24 concrete blocks making up the 37-foot (11.3m) circle. Further out again, is the 90-foot (27.4m) circle represented by another 24 blocks (17 of which are visible). This held the tail guy mooring wire which was used to turn the balloon into the wind whilst bedded down. Just beyond the 90-foot circle, in the southern section of the mooring, a hardstanding for the winch lorry would have stood, and just to the north of this the five hauling blocks located between the 37-foot and 90-foot circles are still in evidence. Item B consists of the domestic accommodation and light anti-aircraft gun post attached to the barrage balloon site. Located to the north of the mooring circle, three concrete bases for temporary hutting and a square, brick-built building with blast wall, flat concrete roof and internal metal shelving measuring 3.59m long, 2.61m wide by 3.02m high, are still extant. To the west, are the remains of a small pen-annular earthwork, measuring approximately 4.60m in diameter, which would have housed a light anti-aircraft gun.

The monument is of national importance for its potential to enhance and illustrate our knowledge of the development and operation of barrage balloon sites as a form of air defence during the Second World War. Barrage balloon defences are known to have been sited at Cardiff, Newport, Barry, Port Talbot, Swansea and Milford Haven. Most sites have been cleared and subsequently developed. This is a rare and mostly complete example. The well-preserved site may be expected to contain archaeological information concerning building techniques, layout and functional detail. The site benefits from surviving documentary and aerial photographic sources, which demonstrate the chronology, layout and function of the site. The squadron Operations Record Book preserved at The National Archives shows that the site is known to have been crewed by the Women's Auxiliary Air Force and is a significant example of women's contribution to the war effort, taking over from a male crew so that they could be directed towards frontline duties.

The scheduled area comprises the remains described and an area around within which related evidence may be expected to survive. It is centred on OS NGR SS 68747 94585, is an irregular D-shaped polygon on plan and measures 76m E-W by 79m transversely.