In all probability your Forsyth dirk was made in Sheffield (or possibly London). Back in the day many firms (including Wilkinson Sword) supplied swords and dirks to all of the top quality outfitters, both in Scotland and England. These "tailor swords" were marked with the name of the retailer rather than the actual maker. All swords supplied to the trade by Wilkinson were numbered on the back of the blade at the ricasso; some, but unfortunately not all dirks were also numbered at Wilkinson's. Judging by the quality of the etching it is obvious that both of these dirks are strictly "top quality".