captainsmiffy,
that is how I always understood QNE. I never used it in 30 years of controlling in the U.K.
The first NATS 'fam flight' I ever did, was in the cockpit of a BEA Trident 3, in fact it was the same a/c that is now preserved at EGCC. Sitting behind the captain, as a newly-valid ATCO, I asked him what advice he could give me, to make his job that bit easier?
I remember him mentioning something along the lines of "always use the term 'flight level' when appropriate"........So I did, and passed that advice on to all the u/t ATCOs I met later on.
Much later on, The U.K. introduced the term 'degrees' for heading instructions, and 'altitude' for QHH-based level instructions. Both were initially a pain to keep saying on the R/T, but, hey, they seem to work.
Altimetry took up a fair bit of the ATC Technical Course, back in the 1980s. It still needs to be fully understood today, even with the technology we now have.
As has been stated above, as with every aspect of ATC......"If in doubt, just ask".