British South Africa Police, badged, arm band?

[Phil2M]

Hi all,

Any ideas on this one, please?

The cap badge is attached by its lugs and is gilt plated. Is it definitely an arm band (mourning band)? If so why is the badge attached, is it official (for the death of a Royal perhaps) or perhaps worn by a family member at the officer's own funeral? Or is it the band from a type of headdress?

I can't measure it at present.

Thanks in advance for any help,

Phil