The BBC has a web site where you can browse or lookup British Slang. I guess that’s fulfilling the part of their charter which has them preserving the culture of the British Isles. I like their little disclaimer on the lookup page:
***Please note: the dictionary contains many words that are not used in the politest of conversations. If you search for insulting words or browse through our collection of insulting words, you may be insulted.
This one goes into the, “Legal disclaimers we like” file