BA 893 then LX 339 at Heathrow
Sofia → London → Zurich
Timetable, London time
22:30BA 893 from Sofia at the gate
20:05LX 339 to Zurich leaves the gate
21 h 35 apart on the timetable, overnight
LX 339 leaves 21 h 35 after BA 893 arrives on the timetable: more than half a day, so not a connection we count.