An interesting badge came up on eBay relating to the First Aid ARP section at Standard Telephones & Cables. The company with factories in London (New Southgate and North Woolwich) provided a lot of war related cables that were used in tanks and other vehicles. The factories were targeted by the Luftwaffe.
The New Southgate factory (in Barnet) was also the site of a devastating V1 attack. 33 people were killed and over 200 injured on 23 August, 1944. This is allegedly the highest casualty rate caused by a single V1 rocket.
Read more about this V1 attack
News about interesting insignia, ARP related info and period photos that turn up.