Hello Silver Searcher, you are very very last member here who's knowledge of British dating I'd question, however could you provide your source for your 1824-25 year of the "S" assayer's mark?
It is possible I suppose that Chaffer's Handbook To Hall Marks on God and Silver Plate" by C. A. Markham has been revised, as my copy is nearly aone hundred years old, however it clearly illustrates the 1824-25 year date (London Assayer's mark) as the letter "I" in the shield, not the letter "S".? Thanks J.
p.s. Silver Searcher; I think while waiting I've discovered the problem with my date. Chaffers' neglected to list the Edinburgh letters (pages 1oo and 101) in their shields, except for a few, despite all other letter assayer date letters accompanying their shields. The only match for both s and shield that Markham listed was the London assayer's mark which dated 1813-14. Anyway, the thistle should have been enough to question the printing and stop me in my tracks regarding a hard date. I've learned the book has thankfully been revised since my 1924 copy, which should help keep boneheads like me out of trouble.

Thanks