In one form or another these things abound, commemorating very many things but just my luck that I don't recall ever seeing this particular one, so from that point of view I'm thinking it must have some scarcity interest.
It's been suggested this was issued in connection with the British Derby (Epsom) during the Edwardian period (first decade of the C20), but that may well be guesswork, and I can't find the pattern in my books on pressed glass, and could be wrong but don't think there is a Carnival equivalent.
I didn't know the story behind the superstition ........... something to do with a blacksmith named Dunstan who had an altercation with old Nick. Having imprisoned the devil, Dunstan agreed to set him free only on condition that the devil never went into houses that had a horseshoe nailed to the door...... hence the habit of nailing said shoe onto door to ward off Lucifer and bring good luck. Dunstan went on to become a big cheese at Canterbury Cathedral apparently!
Needless to say the piece lacks any marks. Diameter is about 9.5 inches and something like 1.75 inches deep (c. 240 mm and 45 mm), and assuming British in view of the text.
I've tried the Board's search without luck, so has anyone seen this before, and is the maker known, please. thanks for looking.