WW2 ARP City Messenger Portmouth air raid precautions badge

A very scarce original Second World War period 'Air Raid Precautions badge', large chromium plated circular example surmounted by a Crown, bearing the 'Arms of Portsmouth' in pale blue and yellow enamelling and set on a field of deep blue inscribed 'A.R.P CITY MESSENGER'; the reverse impressed with maker's details 'Caxton N / Plated London'. Very good condition, complete with original buttonhole fitting, very minor service wear to crown otherwise enamel perfect.Height approx 46mm.The City Messenger Service played an important roll in the war, they numbered many Boy Scouts and Boys Brigade members who would act as runners between ARP wardens and headquarters, delivering important messages after air raids had cut telephone lines.