Just to add another sausage in the pan.
K or 'Kay' is often used by sportsmen to abbreviate distance. As in 'a ten kay cross country' (XC) run/glider flight/cycle ride etc.
Have to admit though that having been in aviation for most of my life it's only in the last couple of years that the term 'k' has become common slang for gas turbine thrust rating. Certainly in this part of the world.
