BA 753 then BA 139 at Heathrow
Geneva → London → Mumbai
Timetable, London time
10:00BA 753 from Geneva at the gate
09:35BA 139 to Mumbai leaves the gate
23 h 35 apart on the timetable, overnight
BA 139 leaves 23 h 35 after BA 753 arrives on the timetable: more than half a day, so not a connection we count.