Jack-in-office is a term primarily used in British English.
A jack-in-office is a self-important, rude, and/or petty minor official (or other person holding some authority). The plural is jacks-in-office.
You may recognise the word from the well-known painting by Edwin Landseer called A Jack in Office, and a character in Arthur Conan Doyle’s short story The Adventure of the Speckled Band calls Sherlock Holmes ‘the Scotland Yard Jack-in-office’.
I can’t remember the last time I wrote or received a personal letter. I suspect that, sadly, I am not the only one. 
Business letters, on the other hand, are still sent and received fairly often. Writers often worry over which ending to use with which greeting. Many of the more formal closings are simply no longer used – Your most obedient servant in particular.
If you begin the letter with Dear Mr Smith, Dear John Smith, or Dear John, then you should end with Yours sincerely. If you use the first name only and know the person well, you could use With kind regards, Best wishes, or a variant of these. The choice that you make should reflect the level of formality the letter requires.
If you begin the letter with Dear Madam, Dear Sir, or Dear Sir or Madam, you should end with Yours faithfully. Yours truly is a less formal alternative.
In British English, curb and kerb have different meanings.
Curb: a restraint or something that holds something else back. To restrain.
Kerb: the edging to a pavement (between it and the road) or a raised path.
In American English, the spelling curb is used instead of kerb.
The annual British practice of catching swans on the River Thames and its tributaries, and marking the swans to indicate ownership (by the Crown or a corporation).
The practice dates from the twelfth century when swans were an important high-status food. The Crown still retains rights over unmarked mute swans in open water, but the swans are no longer eaten.
Modern swan-upping takes place primarily as part of conservation efforts, and education is now a key part of the undertaking.
The hyphen is recommend by the New Oxford Spelling Dictionary and other older dictionaries, but many modern uses are not hyphenated.
More details on modern swan-upping can be found here and here.
These words have overlapping meanings to do with certainty and security.
Insure:
Ensure:
In American English, insure is used instead of ensure. It is much less common to see this in British English (and probably to be avoided).
Flare and flair are homophones, and homophones are often confused. Flare tends to be used when the word should be flair. I think this is because we are more used to seeing and using flare (it has a wider range of uses).
Flair
Flare
*Before my time.
This is another post written because of suggestions I have received from readers of my blog (thank you).
My compliments to the chef.
Compliment:
Complement:
The meaning is the same when using the words as verbs. You compliment me on my dress. My shoes complement my dress.
Complimentary and complementary
The difference here is largely the same as above. However, complimentary has an additional meaning to expressing admiration or praise: it can also mean given free of charge.
Complementary means completing or forming a complement, or refers to the relationship between things that go well together.
Spelling
It may help as an aid to spelling to remember that a complement completes something and complete is spelt with an e (as well as the ‘e’ sound when pronounced).
This word does not mean what you probably think it might mean (shame on you).*
Bag-o’-wrinkle is a variant of the nautical term baggywrinkle.
Baggywrinkle: rope yarns (usually old) wound around parts of a ship’s rigging to prevent chafing.
From the pictures I have seen, it looks like a cross between a brush and a mop head.
*Don’t look up baggywrinkle on Urban Dictionary though.
‘Allusion’ and ‘illusion’ are often confused. ‘Elusion’ doesn’t get mixed up with them that often but sometimes it makes a surprise appearance.
An allusion is usually defined as an indirect reference. However, Fowler’s states that it is acceptable to use ‘allude’ to mean ‘refer’.
An illusion is a false appearance or deceptive impression of reality. It can also be a false or misleading idea or belief.
Elusion means the act of escaping or avoiding.
Thank you to Aeryn Rudel for suggesting a new addition to my blog topics – weird hyphenated words!
‘Arsy-versy’ is an informal, primarily British English word. It means backwards, upside down, in reverse, confused or disordered.
I got things arsy-versy.
I probably wouldn’t use it in front of polite company.
Hannah McCall 