While native English speakers have few dramas with the radio, it would be handy to remember that many pilots who are not from an English background are assisted by standard phraseology. There have been accidents where both ATC and the pilot contributed to the problem with colloquial phrasing. As already pointed out "left 250" could either be taken as a level or heading change.
ps. "Leaving" is the correct phrase for a level change when not radar identified.
