Special Constable Armband Help Needed

[Wooffy]

Hi,

I am after some clarity regarding the armband that comes with this uniform. Early members of the Observer Corps (OC) were all enrolled (enlisted?) as special constables, to that end they all wore the Black and White vertical striped armband. Latter ones were bespoke made with the wording "Observer Corps" in red incorporated into the weave of the armband (as shown in the third image). I have come across this image of an OC uniform with an unnamed armband, but it seems to have a metal letter "S" affixed to it - can someone please let me know what that denotes?

Thanks in advance.

[GTB]

Special or Spotter?

GTB