Royal Ordnance Factory, ROF, Blackburn was part of the Ministry of Defence organisations producing components for the manufacture of armaments and arms related equipment from the late 1930 until after WWII.
These S&A units provided safe handling for missiles whilst under transit conditions and safety for operator personnel up to the time of having to be armed.
Bombs and missiles need specific launch conditions to be fulfilled to stop injury and fatalities to handlers during pre-launch.
Most well known missiles from the UK after World War II had S&A units from ROF Blackburn, including Blue Streak, and other weapons used during the Falklands Crisis.
[1] The brochure gives a fascinating snippet into life at ROF immediately after the war reporting that beyween 1946 and 1948 the factory produced over one million alarm clock movements before production once again switched back to the large-scale manufacture of mechanical fuses.