What would happen was if an attack was confirmed, the warning would be given either by RAF High Wycombe (Near London) or Longley Lane (Near Preston). This would be forwarded to Fighter command, the police and the media.
The Police would get the message, "Attack Warning RED" over the same telephone lines as thosed used for the Speaking Clock, then activate the air attack sirens over local telephone lines. The rationale was that in using the speaking clock, it cut running costs and allowed a fault to be detected in time to give a warning.
The media would simultaneously interrupt programming to transmit a warning message teling the public to take cover, which was to be broadcast on all television and Radio stations. The actual message itself was recorded by the chief continuity announcer of BBC