These are narrow gaugerailways at military establishments and former UK Government-owned explosives sites. These locations were often subject to the Official Secrets Act and other government restrictions, so many of them are less well documented.
The industrial use of narrow-gauge railways was quite extensive amongst the various military and civilian explosive factories, for example ICI Nobel's works at Ardeer and the Agency Explosive Factories run by ICI Nobel in the Second World War. To give an example, the Ministry of Supply (MOS) Factory Dalbeattie used gauge with a variety of bogie trucks mostly pushed by teams of three to six women. Stores, explosives, chemicals, rubbish and sewage, were all transported on this narrow-gauge system, which used at least of track.