BA 339 then LX 319 at Heathrow
Nice → London → Zurich
Timetable, London time
12:15BA 339 from Nice at the gate
12:05LX 319 to Zurich leaves the gate
23 h 50 apart on the timetable, overnight
LX 319 leaves 23 h 50 after BA 339 arrives on the timetable: more than half a day, so not a connection we count.