Its prolonged whine induced terror - but also saved lives. The sight of Luftwaffe squadrons appearing on the horizon heading towards Britain triggered them as an early warning to civilians in the sights of Nazi bombers.
They were sounded in our cities, towns, and villages and were a sign to get off the street and dart for cover. But in 1999 after 50 years of service they were culled by the Home Office which ordered them to be scrapped.
But in a village in Greater Manchester one has survived - and now has Grade II listed status. It is mounted on a pole in Cecil Road, Hale.
Many passing it will no idea that it is an air raid siren installed in 1938. It, and thousands of others across the UK, played a vital role in the country's defence network.
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