That's a beauty!

Interesting in that it has the old-fashioned pocket to rear (suggesting it's prior to the 1953 Patent) but a press button/popper/snap which AFAIK comes in a bit later.

I have seen that. If I knew more about when various makers started using that sort of popper I could come up with a better date range.

Is the cantle engraved, or chased? The latter would suggest Frederick Narborough.

In any case I have no interest in sporrans that aren't really practical as sporrans. Were I to acquire that one I'd send it straightaway to MM for a re-bag, a big roomy pouch.