I’m sorry I’ve been ‘absent’ for a couple of weeks, but pressure of other work has meant that this blog had to take second place. However, …
As John Wells says in his comment to my last post, we are dealing with two constructions here: in case, and in case of.
In case, followed by a clause, is unambiguous, and could be replaced in very formal English by the obsolescent or at least highly literary conjunction lest: “Don’t run lest you fall over”.
It is the in case of construction which causes the problems. I wonder if we see here not merely a difference between American and British usage, but a generational difference. I have been asking my friends about the original example sentence that I used, and without exception, those of my age and older are uncomfortable with it, and would prefer my alternative “In the event of fire, do not use the lift”. Adrian Morgan’s suggestion that the ‘knowing smiles’ are from an acceptance that “highly formal language can be funny sometimes” is not the case in my experience.
I’m indebted to Jack Windsor Lewis for reminding me that the OED, 1st edition, has two British examples of in case of meaning ‘in the event of’ (Vol 2, page 143: case: II, Phrases, 10 d). Admittedly this was published in 1889, but the later of the two quotations is dated 1745. There is also an example from Washington Irving, dated 1832. This seems to me to imply that the usage may have become obsolete in British English, but has now crossed the Atlantic again, like so many other usages, and is accepted by the younger generation of British English speakers as quite unexceptionable.
Burchfield’s edition of Modern English Usage has one example each of in case and in case of, (‘Take your umbrella in case it rains’ and ‘In case you want me, I’ll be in my office’) and this example of in case of (meaning ‘if’) confirms ds’s and Philip Taylor’s view that the clause containing in case of should precede the main clause of the sentence. I think this may actually be a ‘rule’ of English, and would explain ds’s feeling that it is more ‘elegant’. It’s strange that while dictionaries and books on English usage give examples, they don’t make this word order explicit, but it seems to work, and could be the reason why the ‘wrong’ order on European notices is so noticeable.