GM638

Tir-Gwyllt Second World War Barrage Balloon Site  

20/03/2024  

Designated  

Swansea  

Bonymaen  

 

 

Defence  

Barrage Balloon Site  

Modern  

The monument comprises the remains of a barrage balloon site which dates from the Second World War (AD 1939-1945). It is located on the lower eastern flank of Kilvey Hill to the west of Crymlyn Bog. The barrage balloon site was one of a network of balloons built to act as a form of air defence surrounding the 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 cast-iron rings for securing ropes and cables. At the centre, a square, concrete-kerbed, central anchorage is surrounded by a small ring of eight rectangular concrete 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. 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 north-eastern section of the mooring, a concrete hardstanding for the winch lorry measuring 9.25m long by 4.80m wide is still extant incorporating two linear concrete strips. A looped road enters the site from the east, and this would have provided a turning circle for the winch lorry. Item B consists of the domestic accommodation and light anti-aircraft gun post attached to the barrage balloon site. The ruinous remains of a small brick-built ablutions block and two concrete bases for temporary hutting can be found on the eastern side of the site. In the northern part of the site, the remains of a small unidentified brick-built building and small, brick-lined, below-ground air raid shelter covered with pre-cast concrete panels exists. Alongside the winch lorry hardstanding, the low pen-annular earthwork of the light anti-aircraft gun emplacement is still visible. 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. It has group value from its association with nearby GM636 Crymlyn Bog Second World War Barrage Balloon Site. Both sites represent the fragmentary remains of the barrage that once protected the Llandarcy National Oil Refinery. The site also benefits from surviving documentary and aerial photographic sources, which demonstrate the chronology, arrangements and operation of the site. The squadron RAF 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 area scheduled comprises the remains described and the area around which related evidence may be expected to survive. It is roughly rectangular in shape, centred on OS NGR SS 68122 94278 and measures 125m E-W by 90m N-S.