They once housed a mustard gas factory
THE munitions works at Other major landscaping underRhydymwyn in Flintshire, taken at this time included the culand its underground warverting of the River Alyn and the rens, have fascinated the excavation of a complex of interpublic for years. linked subterranean, rock-cut tunOnly opened to the public on nels and caverns. select dates in the year, the old Some munitions workers were chemical weapons factory was in selected to aid the scientists workoperation during World War II. ing on this secret weapon.
A stone-walled path leads you It was not until many years later through woodlands to metal doors that they were to learn that they that take you inside the network of had contributed to the first steps in tunnels. building an atomic bomb.
Inside there are dimly-lit pathThe tunnels were also used to ways cut straight into the hillside, store mustard gas. with branches leading off at regular In the immediate post-war intervals to the left and right at 90 period, the site was used to store degrees, creating a grid-like comGerman nerve gas, and it was not plex. until the 1950s when Britain relin
Water covers parts of the floor, quished its chemical weapons with cones and barriers standing at capability that the site as a storage the sides. facility was defunct.
The Valley Works, which now sit However, the site remains on the in the heart of a nature reserve at international chemical Weapons Rhydymwyn near Mold, were conList, and is still monitored as such. verted into a mustard gas factory in From the mid-1960s the site was 1939 by ICI on the orders of Winused by various governmental ston Churchill on the outbreak of departments, its major function World War II. being a buffer storage depot to
Members of Rhydymwyn Valley supply emergency rations and History Society later unearthed foodstuffs, and associated faciliproof the miles of tunnels under ties such as mobile bakeries and the nature reserve would have had canteens. a key strategic role in the Cold War In 1994 the site was closed, and a after a Freedom of Information programme of demolition was request was sent to the Treasury. undertaken, but several major
Historians believe workers made structures, and many ancillary 40,000 mustard gas shells a week at buildings, still survive across the the secret plant during World War site.
II, and research was carried out During recent years, the tunnels which helped develop the first have been opened up to the public atomic bomb. at times for tours.
In 1940, two of the world’s foremost physicists, Otto Frisch and Rudolf Peierls, calculated the building of a Uranium atomic bomb was possible.
But they needed a secret facility in which to test out their theories – and wartime Prime Minister Winston Churchill chose the tunnels near Mold.
The land had been purchased by the Ministry of Supply in 1939 and more than 100 specialised buildings were constructed across the site, linked by an extensive rail network established around a spur off the Chester to Denbigh mainline.