I find it interesting that you measure your desk in mm and not cm. Is that common in metric countries? For me, here in the States, I would say I moved from a 24in to 36in desk (which incidentally is also 2 feet to 3 feet, but I wouldn't use feet).
This is the key thing, i think. There is a convention in some technical disciplines - mechanical engineering, architecture, civil engineering up to a point - that things are measured in millimetres even when they're on the scale of metres. So you get a ceiling that is 2400 mm high, or pilings on a 1500 mm spacing, etc.
I'm not sure why. I suppose it means that the large things are directly comparable with small things that are more naturally measured in millimetres (if your tiles are 300 mm, you need eight courses for your 2400 mm bathroom wall), and you can use single unit on drawings taking in large and small things (the engine block is 900 mm long, the bolts are 12 mm across, on 150 mm spacings).
It probably ties in with preferred numbers somehow:
My assumption is that it is a. more accurate and b. allows you to talk about a 22mm pipe (standard plumbing diameter pipe) in the same unit as a 2400x1200 sheet of plaster board, without having to worry about what to do with the decimal point - pure speculation though.
Ironically people will say “twelve hundred” in this context which is deemed to be of American influence, but in any other context they would more likely say “one thousand two hundred”. Given that the US is imperial this can’t be a trade influence - must be for speed and ease of pronunciation.
This is speculation on my part, but I consider mm better because it allows greater resolution than cm without fractions and makes more sense when you consider cm is the only non-thousandth metric prefix we use for common units (mL,kg,km - dB would be an exception). cm on the other hand is closer in scale to inches and generally easier to estimate because of this.
Source: I asked someone who has a Masters in English and forgot most of what she said, so don't hold my feet to the fire on details.
My point is that non-American English spelling is wrong in many cases, intentionally. So don't go around saying you're correct. You mutilated your own language to appease the French.
If we're going to talk about the deliberate sabotage of orthography, then surely Noah Webster's "thru", "catalog", etc are the most outrageous?
That said, as with metre/meter, we have at least salvaged some Websterisms as adding nuance to the language. In the UK, i write computer programs, but pretend to enjoy opera programmes.