After reviewed copy came back, I protested to my client that theirs had turned all my single inverted commas into doubles, flying in the face of what I called accepted contemporary practice, which employs doubles only for reported speech. Word came back that the client insisted on doubles, which, they said, was standard practice in America.
Are they right? I’d never heard of such a convention, and a few minutes’ googling provides no definitive answer. But I’ll continue to recommend singles, for no better reason than my general instinct to ‘cut the clutter’, and keep everything as clean and minimalist as possible.
None of which, needless to say, affects the primacy of the client’s preference. So long as it’s not unquestionably and definitively wrong, the client gets what the client specifies. You paya da bills, you maka da rules.