Handel (warning system)

Handel was the code-name for the United Kingdom's national attack warning system in the Cold War that was in place between 1962 and 1992. It consisted of two injection sites linked to a series of two hundred and fifty-two carrier control points installed in major police stations; in turn, the control points were linked to several thousand receiver units installed at "warning points" in various police, fire, and coastguard stations, government buildings, hospitals, industrial centres, and Royal Observer Corps posts, with sufficiently remote areas having the units installed in post offices, public houses, churches, or even private dwellings.
A Handel warning console can be seen at the Imperial War Museum in London among their Cold War exhibits, alongside the warning apparatus used by Kent Police.

Operation

If an enemy attack was detected, a key on the left-hand side of an "operating unit" console at one or both of the injection sites would be turned and two lights would come on; the operator would then press and hold down a red button and announce "Attack Warning Red". At the carrier control points, if one or both red lights flashed with a constant alarm, or if a white light flashed with an intermittent alarm, the control point operator was to lift the two red handsets or the black handset, listen for the injection site's "Attack Warning Red", and acknowledge it; they would then pass on their own "Attack Warning Red" to the warning points before activating powered sirens linked to the control point. Those manning the warning points would operate hand-cranked sirens once they had received the attack warning message. The sirens would coincide with the broadcast of a "four-minute warning" on media channels.
Linked into Handel were the twenty-five Royal Observer Corps group controls, also with direct links to the carrier control points. As fallout from an eventual nuclear attack began to descend, "black" fallout warnings could be generated from the group controls on a localised basis over the same carrier wave system. Handel was also intended for use in communicating the eventual "white" all-clear message.
Initial Handel equipment fell under the WB400 and WB600 series of designations; this was upgraded from 1982 onwards to an EMP-resistant equipment line falling under the WB1400 series of designations. WB1400-series receivers were also trickle-charged to ensure that they would work when needed. The "operating unit" console at the injection sites was known as the WB1800.
The Handel system was based around the telephone system used for the speaking clock. The rationale for piggybacking off the speaking clock system was to tackle two problems at once; it reduced running costs and the telephone lines were continually tested for readiness by sharing infrastructure with a public service, meaning a fault could be detected and repaired in time to give a warning.

Warning messages

Message	How it is received	Action to be taken	Notes
Test broadcast	The words "Test call, testing" followed by the message: "A test of the Attack Warning signal will now follow". This would be followed by various signals and then the message: "A test of the Attack Warning signal has just been made".	-	If an attack warning occurred during the test, the latter was to be abandoned immediately.
Attack warning	Warbling note followed by the message: "Attack warning RED!" This would be followed by a minute-long control signal, activating the powered sirens	Sound warning by activating powered sirens/operating hand-cranked sirens, the attack warning would be a rising and falling note.	Attack warning would be broadcast on all television and radio stations by the BBC; the carrier control point operator themselves might be first alerted to a live attack via BBC broadcast.
Fallout warning	High-pitched pip signal followed by a spoken message. For example: "Fallout warning BLACK, London!"	Fire warning maroon three times. Though in some areas, it could have been three gongs, whistles, or even church bells creating one long note followed by two short notes forming the morse note "D-".	Fallout warning would be broadcast on the radio "wherever possible". Could also be given by word of mouth from the police and ROC staff.
Fallout expected within one hour or more	High-pitched pip signal followed by the spoken message. For example: "Fallout warning GREY, Canterbury!"	Fire warning maroon or sound siren producing one long note but interrupted in short succession. Could also be given by church bells or word of mouth from the police and civil defence wardens	Fell out of use by the late 1960s.
All clear	High-pitched pip signal followed by a spoken message: "Attack message WHITE!" A minute-long control tone would activate the powered sirens, though activating these was only warranted if the all-clear message was to apply to all warning districts rather than to a specific district or districts. Hand-cranked sirens would be operated in response to a general all-clear message or in response to an all-clear message applying to their specific warning district.	Sound siren giving a steady note	Further warnings may be broadcast on radio, along with information on aid for survivors and morale-boosting broadcasts.