1939 ARP badge

A.R.P. buttonhole badge.
In December 1937, the British government passed the Air Raid Precautions (or 'ARP') Act, requiring local authorities to ready themselves in case of air attack.
This belonged to my grandfather.
Interesting history to the badge from here.

https://www.ww2civildefence.co.uk/blog/history-of-the-arp-badge