For instance, the links between "correct", "director", "erect", "regal", and "real"are obscure in English, you say.
Latin: rex, reg- = king, ruler. reg- rex- rect- = rule, ruled
correct-cor- is a corruption of con- = together/strongly (when used as a prefix). -rect from reg- = so strongly according to the rule.
director - rect-rule rector (noun) = ruler dis- in all directions so director = ruler in all directions (?)
e- out e-rect = ruled outwards (in fact upwards)
reg- = king so regal = kingly = king-like
real is from res = a thing so is not connected. English dictionaries verify the Latin roots of all these words.
I like all your points, and agree. If one plans an academic career Latin is invaluable. For business I would not know what is required, but a sound command of English is more than essential, I understand from those people I know who are engaged in it.

Warsaw Will, I bow to your superior familiarity with the history of these things, and like what I read. I have no experience of the dull and stultifying teaching of grammar before the reforms, nor of the syllabus for EFL/ESL. I too spent my schooldays in Scotland, however, and in my time the figure of 8% was given for those who went on to university, with many others going on to other forms of tertiary education, of whose institutions a great number have since been reclassified as universities. As to what I think about that and the tenfold increase in the higher degrees awarded, I shall zip my lip.
What I am very familiar with is the business of translation from ever more complex Latin into, therefore, ever more complex English, presenting a perfect scenario for students to find themselves confronted with the challenge of finding the most correct and the most expressive way to render into English a given set of words whose structure bears next to no resemblance to the final choice of a translation. It is an ideal medium for challenging a person to deal with the conundrum : "Here is what you must say, (but it is in Latin), now say it (in English)."
When you say that part of the problem with the 18th century prescriptivists is that some of them tried to force English into a Latin mould, then I find myself calling out "What?", closing my computer down and heading for the pub, where I might or might not try to work out what that's meant to mean!
But I value your splendid and learned and beautifully researched and argued pieces on this subject. My research is confined to reading the newspapers and having learned discussions with equally aged and disillusioned old persons. Meanwhile are we not meant to be confining our deliberations to the correct use of the subjunctive? I use it, I learned about it through Latin, not English, lessons, and I deplore the ambiguity which results when it is not used when it should be.
Politician: "If I left money in a brown envelope ..." readily permits the interpretation that he allows that indeed he may have left it. Politician:" If I were to have left the money ..." makes clear he claims not to have left it, quite a different thing. But he may well mean the latter although he says the former, but then, that's politicians for you anyway, not so?

resumé, or résumé?
I'm with you there, Tango. We don't have accents in English, as we all know, so when we use them in words borrowed from other languages, such as French, why use them? Well, I say, if we do borrow them, let us borrow them intact. Resume pronounced résumé is now an English word, needing no written accents. Résumé with both accents is a French word borrowed by English, unchanged. If resumé is not found in French why would we have it in English? It is indeed amusing that the French do not use their own word for a curriculum vitae, but borrow that term intact from Latin, as do we also when we can't, through ignorance, find the acute accent in Word. I do, anyway.

Warsaw Will: thanks for the corrections to the details which I over-simplified in the hope of keeping my rant as short as possible; you are absolutely right. I guess my figures for private/state students in universities did indeed refer to Oxbridge or at least Russell group of UK universities - figures I took aboard a few months ago from the Daily Telegraph. Those entering all the universities we have these days for all courses in everything indeed do not show the demotic figures I mentioned. And indeed some grammar schools survived the cull in the '70s. And those who won places in them did not do so by lottery but by the much hated 11+ exam which it is usually argued excluded too many too young from the chance of a good education, although it allowed those who were successful to go on to enjoy one.
So only two points: Somerset Maugham whose work I greatly enjoy did not write the pure English attained by his near-contemporary Nancy Mitford, and he did not set out to do so. The other where you mention " I learnt Latin at school and it has absolutely no effect on whether I use the subjunctive or not". Yes, I say, but you do know what the subjunctive is! And Mr Gove probably knows what the passive is, too, and wants to have its use avoided not because of any literary flaws but because he wants action in his department. The subject of his passive infinitive 'to be drafted' is 'letters', inanimate, so that one is okay in his view, I guess.
I insist that the central thesis of my diatribe is that folk grumble and tut about how no one is taught grammar any more, and I say yes, those who learn Latin do. So, for example, the folk who say "I" when they mean "me" have no idea why it is wrong because they don't know their subjects from their objects, nor what a preposition is, so "Tom and me are well glad that Maggie and Jock have invited Sally and I to their do" is grammatically incorrect. It is still fine to say it, of course, if you insist, but if the speaker thinks it is 'correct' it is a shame not to know any better, really. I was intrigued to hear a good old friend tell off another good old friend who had said "They're coming with Jock and me", claiming it should be "with Jock and I". And no, she had not learned Latin either. And no, her interlocutor did not defend her version, as she was too polite, but just let a flicker of smugness show for a second!

Jayles, right on, correct, except that 'anus horribilis' is a joke, of course, annus is a year, as in annual and anniversary (vers- from vert- = turn). Horribils = horrible, frightful and dreadful, but also, colloquially, astonishing and wonderful. When she mentioned it in her speech the Queen took care to pronounce it with a short 'a', as she did not want it possible to seem to make the blue to which you allude. Word order is different and sentences these days, conventionally, have capital letters only with proper nouns. And anus = old woman! and gets a laugh every time.

Jayles, you are right. You should kick off early, the earlier the better. There is a very popular course called "Minimus" featuring what appears to be a Roman version of Mickey Mouse, and it is used at primary level to entertain small people. I do not think that they are frightened by grammar there.
In my Latin course adverbs are introduced right from the start, as they are easy because at first they don't have different endings to worry about. 'Properly' is 'recte' and, because it is an adverb, it describes how you do something (speak English, for example). But proper is 'rectus' or 'rectum, recti, recto, recta, rectae', etc etc (36 permutations depending on what is being described as being proper), so must be brought into play, a few endings a week, over about a year of lessons, as adjectives are, after verbs, the most complex words to learn about in Latin. In the second and third years the pupils learn the other 72 endings for 'more properly', and 'most properly'. Then they know all about adjectives. Meanwhile they have known about adverbs from the start.
That's right. Recte means 'right', too, if we mean 'correctly', doing it right. If we are talking left and right it's sinister and dexter. I wonder what 'lefties' might be. I'll work on it over a beer. That's the fun of Latin: it isn't easy, and you have to think. Those mottos in Latin can be very cryptic.

But I'll tell you what: Latin students know grammar, because they have to if they are to cope with all those permutations and structures. And it's good at providing a rich fund of vocabulary, too, as in dextrous, sinister and correct, all from Latin. Nothing elitist about it, lefties need not fear, obviously.

I take the view that fish is correct, phish is not, I was using your logic to show that it is not sound, and you agree with me. If the dictionary allows one accent on resume where the French one does not, then I go with the French, I am afraid, for that noble language is proud of its purity, and the Academie Francaise has a language committee to stamp out impurities, while English is proud of not being very fussed, sometimes.
And let us remember George Bernard Shaw who would have us think "ghoti" is a way to spell fish, as in enough = gh = f, motion = ti = sh, and I forget why o = i, but it's all very silly, although he meant it. Perhaps 'o' in "simpleton" for example sounds like 'i'.
Why should you not change your name with each piece you send in? Shakespeare would have been proud of you. And as you say, you didn't.

Those of us in the UK and elsewhere who learn Latin learn all about grammar - we have to, in order to make sense of the permutations of the word endings. The only nation I have come across which thinks grammar is daft and takes the view "who cares" is the British, where there is to be found in all too many places a seething resentment against education in general: grammar, incredibly, is thought to be elitist by the lefties (I have often heard them say it is) who seem to have controlled the teaching profession here ever since the '60s, with dire results. For instance people in the public eye such as politicians and broadcasters are now nervous of employing grammatically correct English, including the subjunctive, in public, anxious lest they be condemned as elitist. The few who do publicly speak grammatical English are derided, and even attract dislike, because of it. It's quite extraordinary, really. All other nations respect and admire education but large numbers of Britons seem suspicious of it, and resentful.

o tempora, o mores, as we say.

There would be nothing elitist about Latin if everyone were offered the chance to learn it. As was the case a few decades ago, when a Latin qualification was needed for entrance into university, for example, but for some time now the study of Latin has been confined to private schools where lefties flourish less easily, as they can hardly argue that such schools are elitist and then go and work in them (although there are fifth-columnists who do just that!). Grammar schools which provided a brilliant education without fees were thought to be elitist and so were closed back in the '70s. The difference in educational standards provided by private and public schools is now greater than at any time since the last World War. No wonder there are now so many Etonians in the government, and there are such a disproportionate number of privately educated pupils winning places at UK universities. (I think the figures show that over 50% of university places go to privately educated students, who constitute only 7% of the school population). The fact that they have learned some Latin, and so some grammar, including the subjunctive, is not unrelated to this disparity (which of course has other forces too bringing it about). There are signs that this is all recognised and some public (i.e. state-funded) schools are now running Latin clubs for those who want it.

I'll shut up now, or you might not let me come to the ten-year reunion (or is that for the people arguing about the spelling of resume?).

This man (for it is clearly not a woman) argues that "people have the way they prefer to write it and as long as the meaning is clear it shouldn't matter which way they choose." It is fine then to write 'elefant' or 'phish' or 'kat', it follows. Pish! as Shakespeare (who spelled his name 32 different ways, I am told, according to his mood) would say.

Will, thanks for all that. It is most informative and helpful. I got my dictionary in 1978, I think, and it is well-thumbed after all those years teaching Latin. My original reason, inter alia, (sorry!) for remarking upon Alia's remarkable piece, was: how could one not? (Especially with mercy33's extraordinary, mystical follow-on.) It shouted out for comment, surely, and it was relative clauses and their governing pronouns which sprang to mind at the time, as they do in these circumstances.

(Sprang? Sprung?)

Yes, Will.
All that you say about ‘whose’ and ‘that’s’ is wholly in accord with what I said in my piece, where I cited Alia’s “man whose” with approval by way of comparing it with the sloppy “man that” and suggesting that “man who” is much to be preferred. You just didn’t read my stuff the way I wrote it. I too taught my pupils that ‘whose’ is for people and things...
You are right, too, that Alia need not consider possible grammatical solecisms in her unusual contribution to be important, in the wider scheme of things.
The literary authorities to whom you refer never set out to demonstrate sound grammatical English; that was not their purpose at all.
The reference works which you cite seem to be those to be found in the libraries of students of English as another language, and are therefore descriptive of current usage rather than prescriptive about correct usage, as used by purists. My dictionary (Collins) suggests ‘that’ as a relative pronoun in a context such as “the book that is on the table” to distinguish it from another book somewhere else, (restrictive) but “the book which is on the table” to explain it isn’t somewhere else. My dictionary also refers to levels of formality of speech: the more formal, the more the need to use the correct term. That's a bit obvious, really! When teaching others English it won't do to present colloquial language as good enough for formal use, obviously too.
I don’t like ‘that’ in this context at all, as it is sloppy, and would use commas:
The book, which is on the table, ... (explains that that is where it is)
The book which is on the table ... (explains it isn’t some other book you mean).
I taught my pupils about formality and how to avoid ‘that’ in written work. It depends on the level of formality, and written work is formal in my book. Just saying.