No matter how many low grades I give to British-set historical romances written by new-to-me N American authors, I'm not going to give up. Partly because I occasionally find gems (although usually of the series featuring a female detective between the Wars variety though I hold out hopes of finding another Bronwyn Scott), but also because I get lots of inspiration for looking up the histories of word useages. As an example, 'toastie' as a food item, is first recorded in the Glasgow Herald of 1976 so I doubt it would have been used in polite conversation prior to the 20th Century (which is a shame as I'm sure Dickens would have used the word, had it been available to him). Likewise, 'brilliant' as an exclamation or expression of strong feeling dates from around the same time, according to the online OED, which surprises me slightly as I would have placed it a couple of decades earlier, even though my English teacher disapproved of us using the term in both speech and writing.
Who wants to add to my list?
[ETA:] looking up 'smashing' as an adjective or exclamation (1911-ish, apparently), I found this wonderful put down: 1959 Times Lit. Suppl. 2 Oct. 564/2 It is not her fault that the publishers, in big letters on the jacket, promise ‘as smashing a last sentence as we can recall!’ That promise is not fulfilled. The final twist is surprisingly unsurprising.