Most educated American know that the British have different words for everyday things. (Our car "trunk" is their "boot"; our "elevator" is their "lift.") But few of us probably realize how many of those things are known by different words and phrases. This has been brought home to me recently whlie reading novels written by British writers of the postwar period.
For example, "pavement" in British English is the equivalent of "sidewalk" in American English. A "plaster" is a Band-Aid. The "first floor" is our second floor (the entry floor is the "ground floor'). An undershirt is a "vest." Women's underpants are "knickers." A "biscuit" is a cookie. "Chips" are fries (and "crisps" are potato chips). Tea is a hot beveage, of course, but it is also a light meal eaten between lunch and supper. In a theatre, the "stalls" are orchestra seats. On the road, "no tipping" refers to refuse dumping, not an extra payment for a restaurant server—which in any case is included io the "bill" (check).
Then there are the acronyms that British readers are expected to understand. The "W.I." is the Women's Institute (a community organization). A person with a CBE is a Commander of the Order of the British Empire, and may be referred to as "Dame" or "Sir," depending on gender. The two lower ranks are OBE and MBE. Someone described as "C of E" worships at the (Anglican) Church of England.
Colloqual speech is redolant with local flavor (or "flavour"). Rich people are "toffs." If you're "knackered," you're tired. If you're "pissed" or "legless," you're drunk. If you disparage something as "rubbish," it's the equivalent of "garbage," since that's what the stuff in the bin (not the barrel) is called. If you "knock up" someone, you've simply tried to get them out of bed in the morning.
It seems to me that American novelists include few British characters in their works, whereas Americans have a way of popping up more often in British novels. The results tend to be hit-or-miss. Most baffling to me is that British writers inevitably fail to realize that Americans (unless they are attempting to appear over-refined) never say "shall." We say, "I'll go there," not, "I shall go there."
(c) Cathy Curtis 2022