In 1943 the Police devised a scheme for rapid dissemination of urgent operational information – designated ‘Snowball Scheme’. The Scheme was also intended to pass the information to Head Wardens if necessary and messages were to be headed ‘Police Snowball’ if intended for the police only or ‘Police snowball – pass to Wardens’ if intended for Wardens as well.
Routing of messages is shown in the diagram below – messages fro Police only (‘Police Snowball’) in solid lines and messages intended fro Wardens as well (‘Police Snowball – Pass to Wardens) in dotted lines.
Consideration was also given to using the Snowball system to call out the Home Guard in the event of an enemy raid but the results of exercises held
showed the the time taken to collect the Home Guard would be too long - for example in one exercise held in the South East Sub District of London it took four hours to collect 70% of the Home Guard despite prior warning of the exercise and that every available telephone system was used.
Reference: East Suffolk Police Reports, SRO