Gretna, Hm Factory, Eastriggs Explosives Factory, Nitroglycerine Hill No. 4

Canmore ID: 373570

NY26SE 16.04

Centred NY 27021 64762

What remains of the buildings that once formed part of this Nitroglycerine Hill are situated on a ridge, the gradient of which eases gently as the topography levels off in boggy ground to the NNE. They comprise the remains of the bunds of the three Final Wash Houses (NY 26917 64654, NY 27005 64625, NY 27096 64634), the bunds of six Paste Mixing Houses (NY 26938 64815, NY 27026 64804, NY 27114 64794, NY 26928 64735, NY 27016 64726, NY 27104 64715), the bund of a Dry Guncotton Store (NY 27047 64884), and the bunds of three Paste Magazines (NY 26919 65013, NY 27051 65017, NY 27052 65020). In addition, the ancillary infrastructure includes, amongst other elements, the remains of a narrow-gauge and a standard-gauge railway network (NY26NW 46.23, NY26NW 46.24). As the processes involved in the production of Nitroglycerine relied largely upon gravity to enable the movement of the constituent fluids in a continuous direction, all these buildings are carefully arranged in an ordered sequence and so take account of the slope of the ground. In addition, they are deliberately spaced – the bunds of the Final Wash Houses and the Paste Mixing Houses being set between 42m and 55m apart, the Dry Guncotton Store 44m from the latter, while the Paste Magazines are distanced about 88m from the Dry Guncotton Store and 95m from one another.

The grass- and gorse-grown remains of the most westerly and easterly of the three Final Wash House bunds are rectangular on plan with rounded corners and measure between 38-39m from WNW to ESE by 35-37m transversely within earth banks measuring up to 13m in thickness and 3.5m in height. By contrast, the central Final Wash House measures 50m from WNW to ESE by 48m transversely within earth banks up to 18m in thickness and 3.5m in height. Each of the bunds has slumped a little both internally and externally. There is a V-shaped gap on the SSW of the bunds, while the two most westerly bunds have gaps in the NNE offset to the ESE, while the more easterly companion has a gap on the NNE offset to the WNW. Each is approached by the remains of a narrow-gauge railway embankment. All contain a later Nissen hut (NY26SE 16.06) constructed before the outset of the Second World War. The grass-and gorse-grown bunds of the six Paste Mixing Houses to the NNE are rectangular on plan with rounded corners and each measures between 42-46m from WNW to ESE by 37-40m transversely overall within earth banks up to 15m in thickness and 3.5m in height. The two most easterly bunds have entrance gaps on the NNE offset to the ESE, while their four neighbours have entrance gaps in the same side offset to the WNW. Each is approached by the remains of a narrow-gauge railway embankment. The grass- and gorse-grown bund of the Dry Guncotton Store to their NNE measures 35m square within earth banks up to 11m in thickness and about 3.5m in height. There is a wide entrance gap on the ESE offset to the SSW and this is also serviced by the narrow-gauge railway network.

The grass- and gorse-grown bunds of the three Paste Magazines are situated to the N of the Dry Guncotton Store. They are rectangular on plan, but the more westerly measures 42m from N to S by 36m transversely over earth banks 12m in thickness and up to about 3.5m in height, the central one measures 41m from N to S by 37m overall transversely within earth banks 12m in thickness and up to about 3.5m in height, while the more easterly measures 40m from NNE to SSW by 38m transversely overall within earth banks 12m in thickness and up to 3.5m in height. The more westerly has an entrance gap on the E offset to the N, the central one has an entrance gap on the W offset to the S, while the most easterly has an entrance gap on the E offset to the N. They are also serviced by the narrow-gauge railway network which leaves the gaps of the most westerly and central Paste Magazines to run towards the former site of an Off Loading Platform (NY 26855 65048). However, the latter has been destroyed by the road running to the N of the Hills. The most easterly Paste Magazine was served by another Off Loading Platform to its ENE (NY 27123 65047). This too has been destroyed.

The structures associated with Nitroglycerine Hill 4 are referred to in the report (MMW 1919, 145-163, plans in text) outlining the processes involved in the manufacture of the cordite propellant at H.M. Factory, Gretna (Site 3), which was established by the Ministry of Munitions during the First World War. This section of the factory comprised a complete plant for the manufacture of Nitroglycerine. Apart from the bunds of the three Final Wash Houses and those of the six Paste Mixing Houses, the Dry Guncotton Store and the two Paste Magazines, other buildings were also associated with the plant. These included a Glycerine Dump (NY 26947 64515), a Soda Solution Dump House (NY 26960 64514), two Acid Storage Tanks (NY 26973 64511), an Acid Dump House (NY 26974 64517), a Charge House (NY 26974 64533), a Brine Store (NY 27003 64503), a Nitrator Separator House (NY 27009 64537), four Air Storage Tanks (NY 27043 64527), a share of two Wash Water Settling Houses (NY 26813 64712 - shared with Hill No.3 NY26SE 16.3 and NY 27178 64642 -shared with Hill No. 3 NY26SE 16.3 and Hill No. 5, NY26SE 16.5) and their Ponds (NY 26818 64787 and NY 27191 64722 - shared with NY26SE 16.3 and NY26SE 16.5), three Waste Collecting Houses (NY 26910 64839, NY 26897 64756, NY 26885 64696), two shared Rest Rooms (NY 26874 64882 - shared with NY26SE 16.3, NY 27203 64776 - shared with NY26SE 16.5), an Off Loading Platform (NY 26855 65040) and other minor structures such as shelters and latrines. In addition to the report, an undated plan (SUPP 10-39), a series of descriptions of blueprints (SUPP 10-16 3075A, 3076, 3076A, 3077, 3090A; SUPP 10-17 3202; SUPP 10-18 3376; SUPP 10-19 3562; SUPP 10-20 3737; SUPP 10-35 unnumbered blueprint), some actual blueprints (SUPP 10-24 3075, 3076, 3090, 3090A, 3097, 3196, number indistinct 3202, 3208, 3211A; SUPP 10-25 3376; SUPP 10-26 3507, 3562; SUPP 10-27 3737, 3798A; SUPP 10-28 3910; SUPP 10-31 4365), together with ground-based, contemporary official photographs taken during and after construction (MUN 5-297 pt2 321, 333D, 333D, 333E, 336, 337; MUN 5-297 pt3 525-529, 531-536, 542, 713), held at the National Archives at Kew, illustrate the character of the buildings on this Hill. These sources show that the chemicals were brought to the top of the Hill from other parts of the factory (see Hill 2, NY26SE 16.02 for a description of the character of the buildings clustering around the Nitrator Separator House in this area and for the architecture of the Final Wash Houses, the Paste Mixing Houses, the Dry Guncotton Store, the Paste Magazines and the Off Loading Platform). Hill No.4 shared the more westerly of its Wash Water Settling Houses and associated Pond with Hill 3 (NY26SE 16.03), while it shared its Paste Mixing Houses, Dry Guncotton Store, Paste Magazines and the Off-loading platform with Hill No.5 (NY26SE 16.05).

This Nitroglycerine Hill fell into lot 491, which was offered for sale by auction 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 ruins of the Glycerine Dump, the Acid Dump House, the Brine Store, the Nitrator Separator House within its bund and the dwarf walls of the Air Storage Tanks are visible at the top of the Hill on an aerial photograph (M124/13 04122) flown on 19 August 1940. In addition, the three Final Wash House bunds, the six Paste Mixing House bunds, the Dry Guncotton Store bund and the two Paste Magazines bunds, together with the foundations of the Off-loading Platform are also shown on this photograph. However, Nissen Huts (NY26SE 16.06) had already been introduced into these bunds. Another aerial photograph (CAM/031 06211) flown on 13 October 1942 shows that all the buildings at the top of the Hill had been destroyed.

Visited by HES Heritage Recording (MMD and ATW), 7 September 2022.