This is not so far from what the word used to be about before it became the Jack-of-all-trades it is today, for a style was once a writing instrument. Or, more precisely, something with a sharp point (a stilus in Latin) such as could be used for making marks on a tablet of wax. And, by extension, a piece of writing; and, by a further metonymy, the way in which it was expressed, rather as one might say of a cricketer that he was a reliable bat.
So far so good. But then the word got above itself and was allowed to take on roles for which it had never been intended. From being about the manner of writing, it graduated to the manner of almost anything, such as architecture or horsemanship or the hang of a neighbour's curtains, by which time it had become a bit of a snob. Everyone had a style, but not everyone had style; I'm not sure when this distinction arose, but it had certainly begun to make itself clear by Jane Austen's day, though Austen herself was not too keen on people with pretentions to "style", tout court.
Anyway, we now have at least four common applications of the word: to sports, arts, letters and so forth; to conventions, like "house styles" or how to address an earl; to a way of doing things in general ("Don't like your style"); and to a classy way of doing things ("What style!"). Mr Dacre was using it in this last sense, at least I think he was.