You don't have to be a monarchist to like this article from the UK paper The Independent: God save the Queen's English: Our language is under threat from ignorance, inverted snobbery and deliberate 'dumbing down'. Excerpt;
The Queen's English, with correct grammar and vocabulary, can be spoken in many accents, say Indian or Australian, and in regional British accents such as those used in Birmingham, Newcastle or Glasgow. There are extremely good users of the Queen's English in Sweden, Sri Lanka and Singapore, and very bad users of it in London, Oxford and Cambridge.
There is much ignorance, carelessness, inverted snobbery and deliberate "dumbing down", as if bad English is more socially acceptable than good English.
Standard English should be used when writing business letters, essays, reports, job applications and on all formal occasions. Most people here use it automatically nearly all the time, without consciously thinking: "I am using the Queen's English."
Other forms of English are completely acceptable in appropriate situations. For example, in plays or films involving characters with strong regional or ethnic dialects, the author would not write standard English for them.
A problem with non-standard English is that it can cause confusions. For example, in Malaysia, to have an "off day" means to have a day off, not a bad day, and to "chop" a document means to rubber-stamp it, not to cut it. In Britain, one finds people using "sick" or "wicked" to mean good, with great scope for misunderstandings.
Deviations from the Queen's English include errors in grammar, spelling, punctuation and word choice. I heard a man on a train say: "Me and him gets on great". The two pronouns should be in the subject case, not the object case; the verb should be plural as there are two subjects, and "great" is an adjective, when an adverb is required. One should put oneself last, so the correct version would be: "He and I get on well."
One can have a sentence that is grammatically correct, but ambiguous, such as: "This room needs cleaning badly" or "Mary told Jane that she was pregnant." The former would be clearer as, "This room badly needs cleaning," because word order affects meaning. In the latter, the pronoun "she" could apply to either woman.
The world of advertising often uses corrupted English, as in the slogans "Beanz Meanz Heinz" and "Drinka pinta milka day". Odd spellings are used, such as "lite" and "nite", perhaps to catch the eye by being unconventional. These should be avoided.
It is repeatedly said that English is a living, changing language. We do need new terms for technology or new phenomena, and English has such a large vocabulary because it has absorbed words from many languages. The Queen's English is not fossilised and takes in new words, phrases and usages, but it should not embrace usages which blur meanings.
For example, we have clear distinctions in meaning between to effect/to affect, disinterested/uninterested, imply/infer, their/there/they're, defuse/diffuse, complimentary/complementary, fewer/less.
We lose precision and clarity if we lose those distinctions, and confusions of such words are extremely widespread.
To which I reply, "Hear, hear!" (And not "Here, here," which I see too often in online debates.)