National Filling Factories
WWI The Royal Arsenal at Woolwich was responsible for filling shells but could not keep up with demand so, in July 1915, the first National Filling Factories were opened at Aintree and Coventry.
By the end of the war, eighteen factories were engaged in filling shells. The Principal Architect to HM Office of Works, Frank Baines, became responsible for the designs of all of new facilities.
The actual filling was a simple process but very dangerous work and was mainly done by unskilled women workers. One of the problems was TNT poisoning which led to toxic jaundice causing fatalities as well as turning the women's faces a bright yellow; this earned them the nickname of canaries".
In 1915 the frequency of premature explosions led to the discovery that a large stock of gaines (a tube filled with explosive, connecting the nose-cap of a shell with the TNT filling to ensure that the fuse successfully detonated the contents of the shell) sent from America had left-hand screw threads instead of right-hand threads, and so tended to come unscrewed as the shell rotated in flight. To prevent this from happening, the screwed-in gaines had to be stabbed in two places with a cold chisel and hammer to break the thread to prevent them from unscrewing in flight. The women workers at the NFF at Hayes undertook such risky work. 
No. 1 NFF Leeds - Barnbow
Construction started: 13 September 1915. Contractor: W. Irwin and Co Ltd. Opened: March 1916. Area: 296 acres. Munitions: filling 18-pdr. to 6in shell and QF, BL type cartridges. Barnbow was the first of the 18pdr QF filling and assembly plants. By August 1918 the plant produced 50,000 shells weekly. The workforce peaked in March 1917 at 13,315 employees, of whom 12,150 were women.
Notes: an explosion occurred in December 1916 which resulted in the deaths of 34 women.
No. 2 NFF Liverpool - Bland Park Farm - Sefton
Construction started: 18 October 1915. Contractor: Bullen Brothers Ltd. Opened: January 1916. Area: 175 acres. Munitions: 6in HE howitzer, 18-pdr. incendiary and 60-pdr. HE shell. Notes: built close to Aintree railway station.
This was built partly to complete 18pdr. rounds imported from the USA via Liverpool. The site ultimately filled shells (up to 8in), as well as filling and assembling components. A total of 17,340,100 shells of all types were completed during the war, as well as bagged charges, fuses etc. In August 1918 there were 8,599 employees of whom 87.1% were women.
No. 3 NFF Perivale, London (Willesden Lane)
Construction started: 26 August 1915. Contractor: Alfred McAlpine and Sons Ltd. Opened: 1 December 1915. Area: 120 acres. Munitions: detonators, gaines and primers.
No. 4 NFF Georgetown - Erskine (Paisley)
Construction started: 25 September 1915. Contractor: Alfred McAlpine and Sons Ltd. Opened: January 1916. Area: 250 acres, agricultural land. Munitions: filling 4.5in and 18-pdr HE, 12in HE and trench mortar bombs.
No. 5 NFF Gloucester - Quedgeley - See Archive Journal: Issue 58
Construction started: 20 October 1915. Contractor: The Gloucester Constructionists Ltd. Opened: March 1916. Area: 308 acres, agricultural land. Management: local board of management. Munitions: filling 18-pdr. cartridge, 4.5in and 60-pdr. shell, cartridges and primers.
No. 6 NFF Chilwell - Long Eaton
Construction started: 5 September 1915. Contractor: Holland and Hannen and Cubitts Ltd. Opened: January 1916. Area: 208 acres. Munitions: TNT and ammonium nitrate filling 4.5in to 15in shell. Notes: on 1 July 1918, a serious explosion in the Amatol mixing house resulted in the deaths of 134 employees.
No. 7 NFF Hayes
Construction started: 8 September 1915. Contractor: Higgs and Hill Ltd. Opened: 30 October 1915. Area: 200 acres Munitions: detonators, gaines, 18-pdr., 4.5in, 6in howitzer HE and smoke. Notes: also known as Emergency Factory No. 2
No. 8 NFF Southwark, London (Sumner Street)
Existing building with new extensions added late summer 1915. Contractor: John Gray Ltd. Opened: 12 September 1915. Area: 60,000 sq yds. Munitions: filling gaines, Nos. 100 - 103 type fuses, and inspecting protective clothing. Notes: this site was known as Emergency Factory No. 1.
No. 9 NFF Banbury
Construction started: 28 January 1916. Contractor: Holland, Hannan and Cubitts Opened: 25 April 1916. Area: 142 acres. Munitions: lyditte filling factory - H2 mines, 18-pdr., 6-pdr. and 60-pdr. HE.
No. 10 NFF Coventry - Whitmore Park / Foleshill
Construction started: 12 September 1915. Contractor: White and Poppe Ltd. Opened: September 1916. Area: 109 acres, land owned by White & Poppe Ltd. at Whitmore Park. Management: White & Poppe Ltd. Munitions: filling detonators, fuses and gaines.
Poor assembly procedures led to a number of fuse failures in the winter of 1916-17. After an enquiry procedures were improved and the factory number was changed to No. 21 to prevent mistrust of the fuses by frontline troops.
In March 1917 the labour force numbered 3,864 of whom 90.3% were women.
No. 11 NFF Abbey Wood
Construction started: 23 September 1915. Contractor: Kings Norton Metal Co. Opened: January 1916. Management: Kings Norton Metal Company. Munitions: assembling and filling shell, fuses, detonators and gaines. Notes: built adjacent to the company's works at Abbey Wood.
No. 12 NFF Cardonald - Glasgow
Construction started: 18 October 1915. Contractor: Alfred McAlpine and Sons Ltd. Opened: January 1916. Management: Nobel's Explosives Ltd. Munitions: detonators, gaines and primers. Notes: built close to Cardonald railway station.
Construction started: 23 November 1915. Contractor: Mitchell Brothers Ltd. Opened: July 1916. Area: 250 acres. Management: Vickers Ltd. Munitions: filling 6in howitzer, 8in HE and 60-pdr. HE. Notes: These works were destroyed by fire and explosion in 1917
No. 14 NFF Hereford
Construction started: June 1916. Opened: November 1916 and April 1918. Area: 519 acres. Munitions: 18-pdr., chemical, 60-pdr. HE and 6in howitzer HE.
Built as an additional filling factory to allow for the possible loss of the plants at Chilwell or Morecambe. Produced up to 100,000 shells per week (18pdr to 9.2in). Charging of gas shells with HS was also undertaken. Staff in October 1918 totalled 5,758 of whom 66.8% were women.
Notes: closed in April 1918 and put on stand-by, reopened due to explosion at Chilwell. The site was rebuilt in 1930s but some First World War buildings survive.
No.x NFF Luton, Chaul End
Autumn 1916 Summer 1917 Products: Filling and converting fuses Managed by: George Kent Ltd.
No. x Liverpool, Aintree
First production: July 1918. This was an extension of the facility on the Aintree site to handle Amatol.
Products: Filling shell up to 8-in.; filling and assembling components. Managed by Board of Management
No. 18 NFF Pembrey - Burry Port
Opened: 2 July 1915 and nationalised in June 1917. Management: Explosives Loading Co. Munitions: filling 4.5in, 6in, 8in shell and breaking down of defective shell and Amatol recovery. Notes: built adjacent to HMEF Pembrey.
No. 21 NFF Coventry
See No. 10 NFF Coventry
No. 22 NFF Gainsborough
Construction started: 24 November 1917. Opened: 14 February 1918. Area: 143 acres. Management: local board of management. Munitions: for filling sinkers with TNT, and naval work including H2 mines.
No. 23 NFF Chittening