presbycusis - one I know of (a onetime colleague) must have been around 1999. The other (another onetime colleague) was not a formal offer, he was told the post would be coming vacant but may have to be left vacant, depending on funding. He was provisionally offered the place if it was available, but never found out as he turned it down as he did not wish to uproot to the USA without very good employment conditions. I imagine many ground instructors, being often retired pilots/military aircrew are old enough to be fairly settled.
As far as I am aware the Inland Revenue does not collect taxes if you are resident outside the UK. Therefore it is quite safe to declare those earnings here, but seemingly if you stay beyond the two years would have to pay the US IRS all those deferred taxes ...