BA 349 then TK 1934 at Heathrow
Nice → London → Istanbul
Timetable, London time
21:05BA 349 from Nice at the gate
16:00TK 1934 to Istanbul leaves the gate
18 h 55 apart on the timetable, overnight
TK 1934 leaves 18 h 55 after BA 349 arrives on the timetable: more than half a day, so not a connection we count.