The ATCO in question wasn't of Northern Irish extraction was he/she?
I found when I moved over to England many moons ago, I had to slow my speech down so the In-gur-lish peeps could get it all. If I go back to Belfast for more than 48 hours, I find I'm back talking nineteen to the dozen. For many years, I assumed the In-gur-lish were just thick as two short planks.
For the record, SheWhoMakesMyEarsBleed still tells me off if we're in company and she thinks I'm talking too fast.