Unusual Georgian Silver Barrel Vinaigrette

When I saw this, I thought it must be a nutmeg grater, but it's a vinaigrette. There is nothing obvious to suggest the grille is not of the period and original to the case. Personally, I've never seen another like it. Georgian silver (not hallmarked) vinaigrette. Well made in the form of a two-part barrel with tight screw-fitting and reeded hoops. The interior (which is not gilded) includes an intricately floral-chased hinged grille to the larger part. There are maker's/sponsors marks to the inside of the bottoms of both parts. The marks are not particularly well-struck and to the inside the case, so difficult to read with a loupe or photograph. I believe them to be the Df mark of George II, London maker David Field, 1743-48. I've seen an identically-cased and marked barrel nutmeg-grater for sale on the internet attributed to him. This would appear to be early for a vinigrette, so it is possible that this is a very good 19th Century conversion. If anybody has a better/different attribution of the maker, I'd appreciate the input.