Unicorn 410 Black Powder box


This query came from an Aussie hunting/shooting forum but no info has popped up yet. Sorry no pics.

[quote] Box marked as follows

Pic of case with Unicorn Black Powder written on it
410 Gauge CARTRIDGES No6 shot

Writing on the side says ~ NB- For a thoroughly reliable smokeless cartridge use the “Speedite.” interesting no?
Bottom of box has 2/- on it, so looks like smokeless was around, but BP was still used, the price of 2 shillings may give a clue to the date, I’m betting it’s about 1920ish.[/quote]

One suggestion was that it may have been a brand used by Harris Scarfe from Adelaide, South Australia.
Anybody have any further ideas? or even better a positive ID?