Swede who has only been in London once here and the only thing that I don't understand is "Crypto-Jewish". A cache of items is a quite common word or phrase to use. Like cache of weapons, something you'd learn just by playhing modern video games. Or reading scifi.
I assume crypto-jewish has something to do with mythical, as in cryptozoology.
"Crypto-" means "hidden" - the name "cryptozoology" was coined by people who think all of those mythical creatures actually exist and are just hiding/hidden from the rest of us.
Crypto-Jews were Jews that could not identify as such because they would be persecuted. I think there is a very interesting museum of Crypto-Jews in Córdoba, Spain.
Aka as “marrano” (https://en.m.wikipedia.org/wiki/Marrano) I’ve been told a telltale sign you might have such ancestry is having a surname named from a city.
I assume crypto-jewish has something to do with mythical, as in cryptozoology.