Sorry I've taken so long to reply – been busy celebrating the end of exams.



The reason I dislike "between you and I" isn't because of the "rules of grammar" per se, but because of the way it came to be so widely used. If a rule such as "personal pronouns are always nominative after the word 'and'" had developed naturally, I'd have no problem with it. But what actually happened was that incompetent, prescriptivist schoolteachers threw a spanner in the works with their misguided crusade against French-style emphatic pronouns, utterly failed to teach their pupils what the underlying issue actually was, and thereby produced a generation of confused speakers who are continually unsure as to whether or not their linguistic instincts correlate with prescriptive correctness. "Between you and I" is a Frankenstein's monster creating by prescriptivists.

I realise that this may seem an artifical distinction given the linguist's axiom that a language is nothing more nor less than what its speakers habitually say, and maybe I am being a bit irrational on that point. But I would point out that there's now no clear consensus between speakers as to when it's appropriate to say "you and me" and when to say "you and I". Prescriptivists saw one clear rule (case-based) being replaced by another clear rule (emphatic pronouns), started a crusade to try and stop it, and we ended up with chaos. So whenever I hear "between you and I", I'm reminded of this stupid meddling and get annoyed, even though it's not the speaker's fault at all.