Although Thorburn in his book, "Coins of Great Britain", 1884, lists a Carlisle halfcrown of this type, this is the first illustration I have seen. It is from the Holbrook Gaskell (1846-1919) sale by Glendining 1921. This is a quality collection of mostly English hammered. It includes three Triple Unites, an extensive run of civil war siege pieces including two Scarborough of the" Broken Castle" issue.
The reverse of this piece purports to be of the two line type where the die was used on both the three shilling and one shilling issues. The typical die crack is present but curiously no pellet in the centre of the "O" or before the date. Also, there is no small dot below the overhead "S".
It is surprising that no reference to its authenticity was raised by the cataloguer!