ROF Thorp Arch was one of sixteen Second World War, UK government-owned Royal Ordnance Factory, which produced munitions by "filling" them.
[1][2] It was located on the banks of the River Wharfe, north-east of the two villages of Boston Spa and Thorp Arch; and four miles south-east of the town of Wetherby, West Yorkshire in England.
[1] The site was connected to the London & North Eastern Railway line, which was used in its construction and then for supplying raw materials to the factory and for transporting away filled munitions.
Construction work on Thorp Arch began on 18 May 1940 and the completion date was scheduled for the end of July 1941.
ROF Thorp Arch closed down twice: firstly, after the end of the Second World War; and then finally, in April 1958 four years after the end of the Korean War, as a result of planned cuts in the British Army published in the 1957 Defence White Paper.