No idea if this is English or American. Cannot locate this HW mark.
If it’s solid silver, it’s not British, and probably not American (because it’d say Sterling, or 925, or the like). There are no other marks? I’ve never seen them go crazy stamping the same thing 3 times before. I suppose if someone were making the piece themselves for themself they’d not have to get it hallmarked, but that’s the only reason I can think of for not having marks on solid silver.
No other marks, and the owner is claiming it’s 18th century hence the lack of sterling marks.
It can’t be English 18th C solid silver because there’d be the Lion Passant, city mark (like London, Birmingham, Sheffield, etc.). The stamps do not look in any way like 18th century marks, for one thing, they’d be more worn down. I have serious doubts that it’s sold silver.