National Filling Factory, Banbury, officially called National Filling Factory No.9 was a Royal Ordnance Factory filling factory, building during World War 1 and located in Banbury, Oxfordshire.
At the outbreak of World War 1, the Ministry of Munitions were looking to create a number of munitions production facilities quickly and cheaply. It acquired a series of sites large sites in semi-rural locations, ideally quite level, which were close to nearby railway lines for both transportation of product and workers.
A site of 100 hectares (250 acres) was acquired by the Ministry on 15 June 1916, located east of Banbury beyond the Bowling Green Inn on Grimsbury’s Overthorpe Road. It had good connections with the former-LNWR railway which went eastward out of Banbury Merton Street railway station. Laid out to a standard design, the site encompassed:[1][2]
All components were produced elsewhere, with the facility responsible for final production: inserting explosive into shells, and fitting detonators. Shell filling began in April 1916, with the site exclusively focused on using Lyddite explosive in production. From June 1918, alongside the supporting plants at Chittenden and ROF Rotherwas, all three were supplied with dichloroethyl sulphide by the National Smelting Company at Avonmouth Docks, to produce mustard gas shells.[3][4] Under the management of Captain H.W. Snowball, at the height of the war the average output of shells from the facility was 70,000 per week,[1][2] giving employment to 933 men and 548 women.[5] Through their work, there was always the risk of a yellow skin discolouration, hence the locals called the female workers "canaries".[5]
After the cessation of activities, the site was mothballed from December 1918. Used by commercial clients who were contracted by the Ministry of Defence to strip down and scrap excess military equipment, it remained in operation as a commercial facility with a vastly reduced workforce until 1924.[5]
After that time, the MoD stripped the plant of its machinery, used mainly to keep the similar facility at ROF Rotherwas operational.[1][2] By the early 1930s, little was left except the buildings and the connecting ends of the railway sidings, and the site began use as an early urban-scale military training facility.[5] Training activity increased greatly in the run-up to World War 2, particularly for the Home Guard, so much so that the Nazi Luftwaffe dropped bombs beyond the site at Bowling Green in 1940, in the belief that the site again was a filling factory.[5]
During the extension of the M40 motorway, excavations at Junction 11 for Banbury revealed a number of former facility structures and buildings, which took a considerable amount of effort and decontamination to remove. Most of the former site now west of the M40 has been consumed by the expansion of Banbury.[5]