I have a tea service with a couple marks. There’s a registration diamond which I think means metalware Feb 22, 1872, Bundle 2.
There’s also a clover/shamrock (clearly not a cross on the other pieces) and what looks like a partially open fan, though it could be a shield or something else.
I’m assuming this is plate since it’s missing the sterling marks, but would love to know the maker or any other info! I picked it up at the Portobello Market over a decade ago, and unfortunately don’t have any details.