BA 553 then TK 1932 at Heathrow
Rome → London → Istanbul
Timetable, London time
16:35BA 553 from Rome at the gate
16:10TK 1932 to Istanbul leaves the gate
23 h 35 apart on the timetable, overnight
TK 1932 leaves 23 h 35 after BA 553 arrives on the timetable: more than half a day, so not a connection we count.