UK Attack Warning System Overview
In this section we give an overview of the warning system known by the name HANDEL. Please use the navigation menu details tab to view expanded descriptions of the various elements of the warning system.
The Warning Messages
It was planned to advise the public of the onset of attack, subsequent fallout and all clear by issuing three colour coded messages -- Attack Warning RED, Fallout Warning BLACK and Attack Message WHITE. During the build up to an attack the public were to be advised what to do when the warning sounded. The now infamous Protect and Survive booklets formed part of this advice. Television stations would broadcast advice videos for public consumption.
- The Attack Warning RED is signalled with siren sounding a rising and falling note.
- The Fallout Warning BLACK can be given in a number of ways. Three exploding maroons, three blasts of a police whistle or three bangs of a gong.
- The Attack Message WHITE better known as the All Clear is 60 seconds sounding of the siren with a steady note.
Getting the Message Across
The HANDEL network, utilising the existing GPO / Post Office Telephones / BT Speaking Clock distribution system, formed the first tier of a national network for cascading the colour coded warning message to 250 police control points around the United Kingdom. The Air Attack Warning message would originate from a UKWMO Principal Warning Officer in a military location known variously as Strike Command, Primary War HQ (PWHQ) or Air Defence Operations Centre (ADOC) If that were to become disabled, the messages could be sent from the United Kingdom Warning and Monitoring Organisation (UKWMO) Headquarters in Preston. The second tier of the cascade network being a carrier broadcast system, centred on each police control point feeding out to the end user.
Public Warning Network
The UK was divided into 250 areas each with a control point located in a major police station. The police station control unit had duplicate HANDEL handsets to receive the attack message. A third handset would receive warning messages and eventually the all clear from the UKWMO Group Headquarters for that area. The siting of the control point in a major police station was a continuation of the role started in WW2 the police played in warning the public of air raids.
The UK Attack Warning system was a two stage system requiring intervention at the police control point. The officer in the police station control, on hearing the message sent over HANDEL, would then issue appropriate verbal messages and activate electric mains operated sirens. These spoken messages or siren commands modulated a high frequency carrier signal distributed via the main telephone exchange to all the warning points in the area. To provide security against any fault going unnoticed, the carrier was sent over lines used for normal telephony.
At the warning points a signalling receiver controlled the operation of the mains powered siren. These were mainly found in towns and cities but in rural areas the warning would be given with a hand operated siren. Warning points in rural areas were fitted with a speech receiver. The owner of a speech receiver would hear the spoken message from the control point and be expected to warn the general public by hand cranking a siren kept on their premises. People deemed as 'responsible citizens' were chosen to accommodate speech receiver and siren, such as shop keepers, publicans, council officials, vicars, post masters or the local bobby in a police house.