Tom Chivers, "Two cheers for Alan Duncan, grammar fascist", The Telegraph 6/25/2012:
Alan Duncan, the Minister of State for International Development, has become perhaps the first Conservative minister in history to describe himself as a fascist, rather than waiting for someone on Twitter to do it for him.
Specifically, "Lofty", as he is known, has awarded himself the title of Grammar Fascist, in a memo to staff at the Department for International Development in which he warned that using “language that the rest of the world doesn’t understand” damages Britain's reputation. […]
Of course, it's a fine and noble thing that Mr Duncan is trying to do: on the Today Programme this morning, John Humphrys called for him to be given a peerage. But, unusually for a fascist, Mr Duncan has allowed his terrorised subjects the right of reply. The memo ends: “Disclaimer: [Lofty] is always willing to be challenged about his judgement on grammatical standards and will not take offence at a properly reasoned opinion.” I hope that my honourable friend will not mind me challenging him in that spirit. […]
Access and impact, sad though it is to admit, are now perfectly acceptable verbs. "Nouns being used as verbs" in general is such a common practice that there's even a term for it, "verbing" (it is, pleasingly, also the finest example of its own definition). But the point I really want to address is this: starting sentences with conjunctions such as "but" or "however" is completely fine, and has been used for literally centuries. There are a solid 1,558 examples of sentences beginning with "But" in the King James Bible alone, and a further 12,846 starting with "And". ("Does God want you to use more initial conjunctions?", asks Language Log, cheekily.)
The "however" rule is particularly odd. The Elements of Style, by William Strunk, rules against the form "However, birds can fly", prescribing instead "Birds, however, can fly". There seems to be no reason for this, and even when he was writing in the early 20th century it was a false rule: Language Log points to Bram Stoker's Dracula, The Call of the Wild by Jack London, The War of the Worlds by HG Wells, and Heart of Darkness by Joseph Conrad, roughly contemporary works which regularly use the "However…" form. It seems, like the injunction against using "Hopefully" to modify a sentence, or not ending a sentence on a preposition, to be an arbitrary convention created by self-appointed language guardians.
But what Mr Duncan is doing is creating a style guide for DFID, not prescribing correct English for the nation. The department is his fiefdom, and he may impose whatever arbitrary rules he wishes. In fact, to create a unified style for DFID, he has to. I notice he spells "judgement" thus, while we spell it "judgment". Neither is more right than the other, but if you want everyone in your organisation to write in the same way, then you have to pick one, arbitrarily. It's a matter of taste. And if he finds sentence-initial conjunctions ugly, then he is within his rights to ban them from DFID communications.
I have to note that Mr. Chivers is wrong about The War of the Worlds — Geoff Pullum found no sentence-initital howevers in that work. However, I can restore the balance by citing a post ("The Evolution of Disornamentation", 2/21/2005) documenting initial howevers in Henry James and Mark Twain.
And in fairness to William Strunk, I should note that he did give a sort of an argument for avoiding sentence-initial however:
When however comes first, it means in whatever way or to whatever extent.
If we interpret this as a statement of fact about elite usage, it's simply false. It was false in 1918 and it remains false today. But perhaps Prof. Strunk meant to suggest that sentence-initial however should be restricted to those meanings in order to avoid avoid ambiguity. Arguments of the form "Let's redesign English by fiat to make it better" are almost never effective; but this particular instance is also illogical and even silly, since however in the cited senses can occur in sentence-medial positions as well:
Generally a father, however foolish he may be himself, does not command foolish things. [Saint Chrysostom's Homilies on Galatians, Ephesians, Philippians, Colossians, Thessalonians, Timothy, Titus and Philemon]
I was to feel awe for the bit of parchment in the mezuza over the door; to dread lest a bit of butter should touch a bit of meat; to think it beautiful that men should bind the tephillin on them, and women not,—to adore the wisdom of such laws, however silly they might seem to me. [George Eliot, Daniel Deronda]
Indisputably Mr Home owned manly self-control, however he might secretly feel on some matters. [Charlotte Brontë, Villette]
We are not formed for enjoyment; and, however we may be attuned to the reception of pleasureable emotion, disappointment is the never-failing pilot of our life's bark, and ruthlessly carries us on to the shoals. [Mary Wollstonecraft Shelley, The Last Man]
Thus the ambiguity remains — but in any case, it's almost always quickly resolved by the context.