Thanks, Pat. I watched it land on the airport webcam!
The airports', and consequently Flightradar24's, arrivals/departures systems take a few weeks to catch up. Doncaster showed the plane going but not coming back, and Corfu showed it arriving but not departing. Flightradar24 had it scheduled, but not with it's flight number, so didn't show it departing. I managed to catch it just north of Durres on the Albanian coast, so I had the aircraft call-sign (G-FDZD) and you can put this into the search box. So it didn't vanish out of the known universe as the timetables indicated.
All part of the fun. Not so much fun for a Scottish woman, who was very happy posting on the Nafsika Facebook page that she'd just booked to stay there with her daughter in August. A few hours later she reported that TUI had cancelled it, claiming that it was because of government travel advice. That's obvious cobblers, because TUI has sent loads of planes to Greece today. I think the technical term is "bums on seats".