I just got this back from NGC. I have no real information about it other than what is listed on the insert. I picked it up at the NYINC show earlier this year because it was interesting. The dealer (Karl Stephens) I purchased it from called it "very scarce". The obverse features a 6 point star. The reverse features a Roman garbed minter preparing to strike a die. A dolphin is along the edge. The coin is 25MM, minted in iron, and has a scalloped edge.
That is very nice, there is one listed on Coinarchives: Royal Mint Trial Die 1927, not listed in Haffner, this British Royal Mint Trial Die features a Star of David with date 1927 on the obverse, and an ancient Greek moneyer with "Britannia Moneta" on the reverse. It is not completely clear if this issue was intended as a trial die for the Palestine coinage, but 1927 was the initial year of the Palestine Mandate series, struck at the Royal Mint. first we have seen in the market. From the Lake Pearl Middle Eastern Collection. Estimate: 400-600 USD rim on yours is different and they have different dates.
I haven't seen it before either... nice! I really like the obverse-- it's "different enough". Thanks for sharing. Great find.