Answer:
The 1927 British Florin (Two Shillings) was not issued as a general circulation coin, it was only released as a "Proof FDC" and a "Matt Proof FDC" coin and there were only 15,000 minted.
The Matt Proof FDC coin is described as being of the highest rarity.
The Proof FDC coin would perhaps be described as being scarce.