Isn't tonnes (tonne) the Middle English spelling of tons (tons) , and is this still the current British "Commonwealth" usage? See the last paragraph of this article from an Australian Reuters report for an example:

http://edition.cnn.com/2003/WORLD/asiapcf/auspac/08/18/aust.fisheries.reut/index.html

Tonne is not just spelled differently to ton, it is a different weight, used here to mean 1,00kg in the SI.

Although I can't figger what the SI is; indeed, a tonne is aka a metric ton.

can't figger what the SI is

That's cuz it's from *that *language.

Oddly enough, usually people here say "SI system" which is redundant (Système International).

"people here say 'SI system' which is redundant (Système International)."

This is very much like people here in the Colonies who, when referring to the unique numbers by which automobiles are identified, say "VIN number" which translates "Vehicle Identification Number number."

Yeah, Bean, and almost nobody here calls it the SI at all, but using its official name, and using it properly, was a gesture to the Francophiles south of y'all, seeing as how they're one of about 5 countries on the planet who don't use it.

Francophiles south of y'all

Yeah, I spent last week working with a buncha Engineers who are stuck in the Imperial system because everything is made in the US, and is thus in inches and feet. Buddy would say, "I think it's about 6 feet deep", or "It's 31 inches below the surface" and I would sit there converting that to metric in my head so I could say "Yes, deep enough," or "No, add more water." (Since of course I've worked out the operating parameters of my sonar in metres, not feet!!!)

Which, tying it all together, would give you the provenance for "echoes of cheese eating surrender monkeys". No doubt ...