I’ve noted in the past examples of British writers (unwittingly?) putting Britishisms in the mouths of American characters. Actually, I’m surprised it doesn’t happen more often, as well as the opposite case of American writers having British characters utter Americanisms. There are so many big and small differences in the dialects: how can we possibly be aware of every case where our friends across the pond say it differently? An example that comes to mind is British “driving license”/American “driver’s license.” If I were writing a novel and didn’t happen to be obsessively attuned to such things, I would certainly have a British character say “driver’s license.” A copyeditor (subeditor in BrE) might catch it, but he or she might not.
My latest examples come from a very good novel (in my opinion) called Trio, by the very good English writer William Boyd. There’s an American actress in whose mouth Boyd — I am sure unwittingly — puts two Britishisms in one sentence. He has her describing her role in her current project: “I’m meant to be a famous film star who’s making a film in Brighton.”
“Meant to” for this particular connotation of “supposed to” is pure British. And an American would say “movie star” instead of “film star.” Of course, it’s possible that Anny, as a when-in-Rome sort of thing, has adopted these expressions, but that’s pretty subtle (and there aren’t any other ones).
I was at first going to accuse Boyd of another slip. At one point, this character, Anny, says, “Now I have the money. Everything’s fine.” I initially read that as one sentence: “Now I have the money, everything’s fine.” Americans would say “Now that I have the money…” but a British locution (which Boyd’s British characters all use) leaves out the “that.” However, Anny’s dialogue, in two sentences, is two separate thoughts, and perfectly American. So we’re good.
And full marks to Boyd for having Anny say “cookies” instead of “biscuits“!
Note: As a commenter pointed out, I was not strictly correct in describing William Boyd’s nationality. Here’s what Wikipedia says:
“Boyd was born in Accra, Gold Coast, (present-day Ghana),to Scottish parents… His father Alexander, a doctor specialising in tropical medicine, and Boyd’s mother, who was a teacher, moved to the Gold Coast in 1950 to run the health clinic at the University College of the Gold Coast… In the early 1960s the family moved to western Nigeria… At the age of nine, [Boyd] went to a preparatory school and then to Gordonstoun school in Scotland, and, after that, to the University of Nice in France, followed by the University of Glasgow,…and finally Jesus College, Oxford.”
He currently divides his time between London and a farmhouse in southwest France.
notoneoffbritishisms.com 
Yes, we Brits do say ‘driving licence’ but we spell it with a ‘c’.
Yes, “driving license” is a straightforward error. Correct British use is a ‘c’ for the noun, an ‘s’ for the verb: “licensed to kill” but “poetic licence” – whereas Americans would use an ‘s’ in both cases.
I believe Boyd is a Scottish writer, not English.
I watched “Notting Hill” recently, and Julia Roberts’ character, an American, used several British terms. “A bit” instead of “a little”; “Is that to do with …?” instead of “Does that have to do with …?” I just looked at the script, and it even has her saying “mum” at one point 😆
It’s a long time since I was a sub-editor, and things may have changed, but my impression is that in British book publishing “copy-editor” or just “editor” is fine, and that sub-editor is a newspaper term.
I’ve been both – first a sub, and more recently a copy-editor. The two functions are not entirely the same, though. In journalism, time pressures made the process much more immediate, whereas in book publishing the copy-ed can quite often afford to spend time helping the writer polish their work. Incidentally, I wrote “made the process” above, because it seems to me that sub-editors have become rare creatures.
Ironically, I always thought using “that” was more a Britishism, not an Americanism. In fact, I probably use it more than I omit it. It is enlightening to learn it is an Americanism.
Yes, I think I would use “that” too.
In fanfic, writers regularly get someone to do “Britpicking”, that is spotting all the Americanisms and changing them. This is separate from volunteer beta-readers (which is the fandom equivalent to editors and copyeditors).
There isn’t a specific name for the reverse role, but it does get done.
There’s is the possibility that Americans in England speak English to make themselves understood by the natives and not wanting to be mocked for using ‘cookies’ when they mean ‘biscuits’ eg ‘Do you have any Chocolate Digestive cookies?’.
I’ve often wondered why few authors apparently bother to run the words they attribute to foreign characters past natives. I’ll forgive Edgar Allan Poe’s dodgy French – he wrote the Dupin stories in 1840s US. But how Tom Wolfe could get his British hack in the Bonfire of the Vanities so wrong is beyond me. There was no shortage of Englishmen in New York in the 1980s (Sting was not alone). At least it seems Boyd tried… Thanks for pointing out the shortcomings. Authors should be prodded that way!
“Cookies” is used in the UK… They are sold as “cookies”, too.
https://www.tesco.com/groceries/en-GB/search?query=cookies&icid=tescohp_sws-1_m-ft_in-cookies_ab-226-b_out-cookies
Yes, cookies sold in Britain are rich, large, US-style delicacies. The franchise Ben’s Cookies has outlets from Brighton to Edinburgh.
Yes, cookie is used in the name of some biscuits. But Brits very rarely use the term generically to mean biscuits.
I think American cookies are generally softer than British biscuits, although it’s not a hard a fast rule, given Jaffa Cakes and Fig Rolls etc.
Although Brits have Driving Licences and not Drivers’ Licences, the term “Drivers’ Licence” has leaked into the language from US movies and TV series.
As have so many ‘Americanisms’. The reverse is true too, including adoptions from Aussie English (“no worries”). Because, well, social media.