History

For full history and analysis of the site and an explanation of the chemical processes see the Birmingham Archaeology report cited below.
The Ministry of Supply Valley Works, Rhydymwyn was built to produce mustard gas for military purposes, and to assemble, charge, and store chemical weapons. Important research took place here in the early development of atomic weapons.
In response to the use by Germany of poison gas in the First World War, Britain developed chemical warfare capacity. As war threatened again in the later 1930s, the Government, in association with industry, developed a series of new plants. Work at MS Valley began in 1939, and the site became operational in 1942. It continued to produce mustard gas until the end of the War. The works were run by ICI on behalf of the Ministry of Supply. After the War, stocks were gradually decommissioned.
The works was developed on a large site with distinct zones for production of mustard products, filling of shells and bombs, arming the weapons, and storage in tunnels in the hillside, as well as laboratories and administration areas.
Three plants were built to produce the Pyro variant of mustard gas and and two plants to produce the Runcol variant. Although two of the Pyro plants were commissioned they never went into full production. The third Pyro building was used for research in connection with the enrichment of uranium.
This building, R3, was built for the production of the Runcol variant of mustard
Another building, R4 to the same design formerly stood further north. Both buildings produced large quantites of Runcol.

Exterior

Rectangular building with concrete frame with infill panels of red brickwork laid in English bond. Flat roof. Facing roadway, six bays; the first and fourth (from SE) are broader. At SE end, a doorway (narrowed) and at upper level a window with small-pane glazing. SW elevation has 2 low rectangular blocks which were pump room and syrup room; stairs between. NW end has at upper level a window (reduced in size).

Interior

Divided into 2 areas. Longer SE area (reaction section) has raised platform on SW side which formerly bore production equipment. At NW end, doorway through to acid generator section. Overhead crane and some internal details remain.

Reasons for Listing

As part of a group of buildings which along with the Scheduled buildings in the Danger Area and the Scheduled storage tunnels [FL210(FLT)] illustrate the industrial processes behind chemical weapons production to an extent unique in the UK. Group value with the other listed buildings on the site.

External Links

• Cadwr Listing
• Wikidata Q29508095

External links are from the relevant listing authority and, where applicable, Wikidata. Wikidata IDs may be related buildings as well as this specific building. If you want to add or update a link, you will need to do so by editing the Wikidata entry.

Recommended Books

• 
  Essex: Buildings of England Series (Buildings of England) (Pevsner Architectural Guides: Buildings of England)
• 
  Old House Handbook: A Practical Guide to Care and Repair
• 
  London 4: North: North v. 4 (Pevsner Architectural Guides: Buildings of England)
• 
  Yorkshire West Riding: Sheffield and the South (Pevsner Architectural Guides: Buildings of England)
• 
  Farrow & Ball How to Decorate: Transform your home with paint & paper
• 
  London 6: Westminster (Pevsner Architectural Guides: Buildings of England): Westminster v. 6