The United Kingdom Warning and Monitoring Organisation, “UKWMO” was an organisation run by the Home Office to warn the public on impending, essentially nuclear, attack.
This leaflet from 1979 attempts to explain what the function of the UKWMO is as the most the public tended to see were the above ground entrances to the three-person bunkers scattered across the UK (a full list here). Within a few minutes the UKWMO was meant to be able to send out a warning to any and all parts of the UK of a pending air attack. It’s secondary job was to plot the ground-zeroes of nuclear explosions and then to plot and originate fall-out warnings.
Given that the UKWMO was staffed almost entirely by volunteers it is difficult to say whether in a transition to war whether the organisation would have worked at all. This is not to cast doubt on the willingness of volunteers to turn up (although in a time of extreme tension no one can say with any certainty people would have left their families to hide down a hole) but whether in the resources available would the system have actually worked? In fact, would it even have been mobilised?
Most of the communications used by the UKWMO were fundamentally based around the public telephone network, especially those linking carrier control points and carrier receiver points as well as the monitoring posts. If one of their main post-attack functions was to monitor and provide fall-out warnings it seems unlikely that the telephone network would have survived in tact sufficiently well for them to do this. It does seem fairly unrealisitc to believe they would have been able to keep going despite the overly rosy-view of the end of the world in this UKWMO film from 1962 “Hole in the Ground.” (often erroneously called “Sound an Alarm” but the original title card – missing from this clip — does reveal the correct name; see BFI collection “COI Collection, The: Vol 6: Worth the Risk?“).
A more serious point has to be whether UKMWO would even have been called up at all in a crisis. To a belligerent, seeing the main nuclear-warning arm of the UK being called up for duty could be seen as provocative possibly even encouraging an early strike. Much has been said along these lines about civil defence for many years; that mobilising organisations like the UKWMO could actually be seen as preparedness for war.
We were all fortunate that the UKWMO was never needed in its active role and at the end of the Cold War it was shut-down permanently in 1991.