The mark is illustrated in Ian Pickford (ed.), Jackson's Silver and Gold Marks of England, Scotland & Ireland, Woodbridge, Revised Edition, 1989, p. 117.
Slip-top spoons originated during the late 14th century. The design was inexpensive and easy to manufacture and as a result these spoons remained popular for over a century. Instead of bearing the hallmarks at the back of the stem near the bowl, slip-top spoons were often stamped with the date letter near the terminal. The location of the mark safe-guarded against one type of "duty dodging." If the date letter had been stamped near the bowl, a dishonest silversmith could add a finial after the spoon was assayed and avoid paying part of the taxes.