Help to identify maker's mark I*S

[joho]

Hi All, not sure where to start on this one!! I am trying to identify the maker's mark on this largish, probably 18th-century, silver patch box with pull off cover. The maker's mark, IS with a star between, is stamped to the inside of the cover. There are no other marks. The only other factor which may help is that there is an applied plaque to the cover with a crest (somewhat rubbed) consisting of crossed oars. This could be a Campbell family crest possibly indicating a Scottish connection. The box is 5cm in diameter and 3.5cm high. Many thanks.
[url=https[url=https://postimagen. The box is 5cm in diameter and 3.5cm high. Would appreciate any help. Many thanks.