Coed y Caerau Auxiliary Unit Operational Base

Cadw's description

Summary description and reason for designation

The following provides a general description of the Scheduled Ancient Monument.

The monument comprises the remains of an Auxiliary Unit Operational Base (Item A), a related Ammunition Store (Item B) and a Special Duties Section (SDS) Station (Item C), which date from the Second World War (1939-45 AD). They are situated in woodland where their location below ground was concealed deliberately. Operational bases and SDS stations were built in the coastal districts along the length of the British coastline where a German invasion was expected. All three structures utilise similar construction techniques, comprising concrete floors, brick built end walls and entrance shafts, together with curved corrugated sheet steel roofs and side walls resting on low brick sills. Item A is aligned E-W and the entrance is located at the E end. The interior is divided into two unequally sized rooms. The collapsed remains of an escape tunnel lead W then S from the W room to an adjacent quarry, now shown by a curvilinear depression in the ground. Item B is located 40m ENE of Item A. It is aligned NE-SW, with the entrance at the SW end. Item C is located 110m SW of Item A. It is aligned NE-SW, with the entrance at the NE end. Internally, the structure comprises of two unequally sized rooms.

The monument is of national importance for its potential to enhance our knowledge of the British Auxiliary Unit and Special Duties Section organisations and the buildings they built and used. Very little is known about these organisations, due to the continuing secrecy surrounding their establishment and the fact that many operational bases were destroyed after the War. While a partial list of operational bases and SDS stations survives for Wales, this is one of very few where the locations are known and the structures are in good enough condition to provide details of construction, form and layout. The remains are well preserved and retain significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits. The co-location of three such structures is unusual and the importance of the remains is further enhanced by their group value.

The areas scheduled comprise the remains described and areas around within which related evidence may be expected to survive. Item A is located at NGR ST 3799 9175. The scheduled area is circular in shape and measures 35m in diameter. Item B is located at NGR ST 3802 9178. The scheduled area is circular in shape and measures 20m in diameter. Item C is located at NGR ST 3766 9147. The scheduled area is square in shape on plan and measures 20m NE-SW by 20m NW-SE.