Gretna, Hm Factory, Eastriggs Explosives Factory, Nitroglycerine Compound, Refrigeration Plant, Boiler House

Canmore ID 374950

NY26SE 17.02

NY 26730 64093 (centred)

This cluster of seven grass-, moss- and nettle- grown building fragments is situated 130m WSW of explosives magazine R54 and 90m NNE of explosives magazine R53 (NY26NW 46.12). The largest is a fragment of flooring (1: NY 26732 64115) is situated immediately N of a bend in the nearby road leading S and 80m W of explosives magazine R54. It is rectangular on plan and measures 21.5m from ENE to WSW by 13.5m transversely overall, but divides into two parts, the more westerly being 0.15m higher than the remainder. A more complete grass- and moss-grown floor (2: NY 26749 64098), which is situated immediately SE of the bend in the road measures 11.5m square. It has been coated with bitumen (see Canmore ID: 374955). Four further grass- and nettle-grown fragments, one a cement capped brick wall (3: NY 26717 64079) and the others small sections of concrete flooring (4: NY 26737 64067, 5: NY 26729 64048, 6: NY 26715 64045) are situated S and W of the bend in the road, while a further fragment of flooring (7: NY 26670 64088) is situated about 45m N of explosives magazine R53 (NY26NW 46.12).

These fragments are located to the S of the Nitroglycerine Compound (NY26SE 17.01) and are poorly described in the report (MMW 1919, 146, 157) by the Ministry of Munitions of War outlining the processes involved in the manufacture of cordite propellant during the First World War at H.M. Factory, Gretna (Site 3). The buildings of which they formed part comprised ancillary structures associated with the production of the Nitroglycerine Hills. These included a Refrigeration House and a Boiler Plant. An undated plan (SUPP 10-39) held in the National Archives at Kew shows seven buildings in this general location, three of which stand N of standard gauge railway lines. These include the largest fragment of flooring (numbered as 1 earlier in this description) which can be identified as part of a Refrigeration House (NY 26715 64118), with Sub-station No.2 (NY 26693 64112) attached to its WSW gable. There is also a Charging Station (numbered as 7 above, NY 26664 64083) and a Machine Shop (NY 26755 64124). In addition, there is a very small building shown between the railway tracks (NY 26743 64105), while the three fragments above (3), (5), (6) to their S plainly formed part of a Boiler House (NY 26705 64063), together with its Chimney and Fan House (NY 26711 64055). A further fragment of flooring (4) formed part a Pump House (NY 26733 64067), while a Water Tank (NY 26738 64055) is shown to its SSE. Blueprints (SUPP 10-24, 3139, 3179; SUPP 10-26, 3507; SUPP 10-27, 3675, 3694, 3704, 3796, 3796A, 3797, 3798A) and ground-based, contemporary official photographs taken during construction (Pearson Collection, 122, 197; MUN 5-239, 141, 209; MUN 5-297 pt1, 134, 189, 191; MUN 5-297 pt2, 285, 333; MUN 5-297 pt3, 374), held at the National Archives at Kew, provide additional information about the character of the buildings. These sources show that the Refrigeration House was a single-storey, brick-built, ridged roofed structure with a centrally placed louvre in the ENE gable. There were seven tall windows in its SSE and NNW elevations, while a double bayed outshot with Belfast roofs was attached on the ENE. Its SSE elevation was distinguished by three windows and a double door, but there were only four windows in the NNW elevation. The Ammonia Compressors were in the main building, and the Ammonia Condensers and the Coolers are in the double-bayed outshot. The simpler outshot at the WSW end of the Refrigeration House is identified as a Sub-station (No.2). Its roof, which was capped with a ventilator, sloped down from ENE to WSW and there was a single door and four windows in the WSW elevation. It contained switch panels and transformers. The Boiler House was a single-storey, steel-framed, corrugated iron clad, ridge roofed building with skylights and a vent extending along most of its length. There were six tall windows in the WSW and ENE gables. Both these gables had sliding doors for the narrow-gauge railway close to the NE and NW corners of the building. The Fan House on the SSE was possibly constructed of concrete, while the chimney may have been of mild steel. The interior contained eight boilers, each with its own dedicated coal bunker, between which ran a narrow-gauge railway track. The bunkers were protected by a canopy on the NNW immediately adjacent to the standard gauge railway line.

The Refrigeration House and the other buildings were offered for sale by auction as part of lot 491 on 22-5 July 1924 (HM Treasury 1924, 89; Carlisle City Archives, DX 170/38), when it was purchased by Greenwood & another of Broomhills, Eastriggs (Carlisle City Archives, DX 2040/3). The auction catalogue indicates that the Refrigeration House measured 41m from ENE to WSW by 23.5m transversely and contained an overhead crane. What was possibly Sub-station No.2 is described as measuring 17m from ENE to WSW by 7m transversely. Most of the buildings in this cluster are shown to have been largely intact on an aerial photograph (M124/13 04135) flown on 19 August 1940, but the Boiler House had been reduced to its foundations, the Machine Shop had been demolished and removed, while the standard gauge railway lines had also been taken up. The Pump House is shown as having been a single-storey structure with a ridge roof and a vent running for most of its length. It had two windows in the SSE elevation. The Charging House was also a single-storey building with a ridge roof and a vent that also ran almost its full length and it had four windows in the ESE elevation. Another aerial photograph (CAM/031 06211) flown on the 13 October 1942, indicates that the Water Tank had also been removed. A later aerial photograph (USN/219/206 0006) flown on 26 July 1963 shows that Sub-station No.2 attached to the WSW end of the Refrigeration House was unroofed. This also shows that there was a double door in the SSE elevation. The Pump House also had a door in its WSW gable, while the Charging House had a double door in its WSW gable. Only small patches of concrete flooring remain visible on an aerial photograph (39/RAF/4701 P0026) flown on the 6 May 1975, but by 1986 a large Water Tank (NY26NW 46.26) on a concrete base (2) had been introduced (Defence Infrastructure Organisation MS plan, Drawer 6/ EBD/SERV/1986) and this is shown on an aerial photograph (DP184487) taken by RCAHMS on the 8 April 2014.

Visited by HES Heritage Recording (MMD and ATW), 22 July 2022.

NITROGLYCERINE REFRIGERATION HOUSE AIR COMPRESSOR AND BOILER HOUSE

The Refrigeration House Air Compressor and Boiler House (NY26SE 17.2) were situated to the S of the Nitroglycerine Hills Compound (NY26SE 17.1). The former supplied the cold brine (a coolant) to two Brine Coolers and thence to the Brine Tanks on each Hill. The Boiler House to its SSW provided the steam for heating the nitroglycerine buildings on all five Nitroglycerine Hills (NY26SE 16.1-16.5).

Information from HES Heritage Recording (MMD, ATW), 18 May 2023.