BA 134 then BA 802 at Heathrow
Mumbai → London → Reykjavík
Timetable, London time
12:35BA 134 from Mumbai at the gate
11:45BA 802 to Reykjavík leaves the gate
23 h 10 apart on the timetable, overnight
BA 802 leaves 23 h 10 after BA 134 arrives on the timetable: more than half a day, so not a connection we count.