ROF Chorley was a UK government-owned, munitions filling, Royal Ordnance Factory (Filling Factory No. 1). It was planned as a Permanent Royal Ordnance Factory with the intention that it, unlike some other similar facilities, would remain open for production after the end of World War II; and, together with ROF Bridgend (Filling Factory No. 2), would replace the Royal Filling Factory located at the Royal Arsenal, Woolwich.