Description and History of Site:-
Royal Ordnance Factory number 8 was an ammunition filling factory covering 642 acres adjacent to the River Wharfe to provide a plentiful supply of water to the site and close to the LNER rail line to facilitate the transport of materials and labour.
The site was first surveyed in February 1940 and the site completed in October 1942 at a cost of £5,950,000, with ammunition production starting in some completed buildings before this date.
The two 1000 person capacity hostels built at Wetherby would not be able to cope with the influx of an expected workforce of 18,000, the majority of them women. The LNER provided the solution by designing a single track circular railway line around the site with automatic signalling, allowing specially chartered trains bringing in workers daily to follow in quick succession. Four platforms were provided at various locations on site to allow workers to embark/disembark close to their workplaces. The empty carriages were then held on site in sidings awaiting end of shifts to return workers to their homes. There were three shifts, mornings, afternoons and nights, with workers rotating their shifts in that sequence.
The factory was divided into 'clean' and 'dirty' areas. The dangerous filling areas and production of the final shell were in the clean areas which could only be reached through a 'shifting house' where all workers changed out of their personal shoes and clothing, and into the supplied protective clothing and shoes. Contraband which could trigger an accidental explosion such as metal hair-clips, lighters and matches and even food where any sugar content could cause a catastrophic reaction with explosives were handed in to be returned at the end of the shift. The dirty areas were the stores or magazines of completed ordnance awaiting shipping.
The site was further divided into different groups of buildings, see the site plan here; http://www.disused-stations.org.uk/features/thorp_arch/index.shtml
Group 1 - Buildings in this group were used for handling the most delicate explosives such as detonators.
Group 2 - TNT and Tetryl, powdered explosive compounds used to make exploder pellets, magazine pellets and exploder bags.
Group 3 - Fuses were assembled here using detonators produced in Group 1 and the magazine pellets from Group 2.
Group 4 - Special blends of gunpowder were produced here for the use in delay mechanisms of time fuses.
Group 5 - Filling of cartridges was carried out here and then sent to magazines for dispatch. The process included filling cloth bags with cordite for breech loading ammunition and filling cordite into individual brass cartridge cases. (see WYK02358 for ROF22)
Group 6 - Smoke producing shells and tracer ammunition.
Group 7 - Small arms ammunition filled.
Group 8 - All the heavy work carried out here such as mixing and filling for large shells and bombs.
Group 9 - All the large storage magazines for completed shells awaiting dispatch. Many of the buildings were protected by earth blast walls and earth covered roofs, all served by an internal rail network.
Group 10 - Test ranges where a percentage of the finished munitions were tested.

Within the factory site was a huge network of internal roadways and rail sidings. There were also 'clearways' which were special roads for transporting components between buildings. Made of gritless asphalt coated with a shellac-like material, swept and washed regularly to maintain a clean smooth surface. Although the factory was not fully completed until October 1942, production started in completed areas before this and the facility was declared open by KIng George VI in 1941.

Post WW2 the factory served as a Ministry of Supply storage depot handling wartime materials returned from overseas.The engineering facilities were used for a period to repair rail wagons as a backlog of repairs had accumulated during the war years.

With the outbreak of war with Korea in 1951, Thorp Arch was pressed into service again in the manufacture of ammunition. The site had lain neglected since WW2's end and urgent site repairs commenced for this purpose.
The main requirement was going to be 20mm ammunition so buildings that could be adapted for this work were quickly brought on line. The American method of production with one building being used for assembly and finishing work was adopted instead of individual buildings being used as previously. This entailed the ends of existing buildings being removed and extended and the areas between roofed over.
Some of the previous workers from the WW2 period were re-employed but training for new workers commenced January 1952 and experience in filling work gained by temporary deployment to ROF Swynnerton, Staffordshire which had stayed in production.
Without conscription it was no longer acceptable to billet workers so they were brought in daily by rail from as far as Hull.

The first 20mm ammunition produced was on 8 February 1952 with 13,263,000 rounds produced in the first twelve months. Eventually once in full production 500,000 rounds per week, in a single shift were produced. By 1953 20mm rounds demand declined and production changed over to rockets and 1000 lb (453kg) bombs. By 1955 the workforce numbered 2000.
By 1957 a reduction in size of the armed forces following the aftermath of the Suez campaign lead to a number of ROF's closing, Thorp Arch closed April 1958.

In 1959 the site was purchased by a consortium of business men with the intention of redeveloping the site as an industrial estate, this opened as such in 1961. Some of the retail stores are located in the former Group 9 magazines on Street 4.
Other areas of the site were developed as a prison and also a storage depot for the British Library.

Further Reading and References:-
http://www.disused-stations.org.uk/features/thorp_arch/index.shtml

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Key Words :- ammunition production

Viewing the Site :- Retail outlets open to the public.

Address :- Thorp Arch, Wetherby, West Yorkshire, LS23 7AU
Grid Ref :- SE 44689 46686
Co-ordinates :- Lat 53.914403 , Long -1.321137
Local Authority :- Leeds Council
Pre 1974 County :- Yorkshire - West Riding
Site Status :- Site extant - Protected status unknown
Site Condition :- Site refurbished to industrial / commercial use
Site Dates :- 1941 - -
Record Date :- 8 April 2020

Copyright :- cc-by-nc-sa 4.0 © Andrew Garford