Leather sporran strap etiquette

[Tobus]

Those double D-ring adapter things appear to be a fairly recent invention.

Because up through WWII Evening Dress sporrans had rings soldered on the back for the chains to clip to:

Hmm, I have an older horse hair sporran (pretty sure it's pre-WWII, my guess was late 1800s to early 1900s) which still has the back pocket but no soldered rings. Just leather belt loops. As you can see, the previous owner hastily cobbled together a make-do version of a D-ring adapter to attach the chain.

I figure this sporran hails from a time when these were still considered daywear, and a plain leather strap would have sufficed. That may explain the absence of soldered fixed rings for a chain.