BA 777 then BA 35 at Heathrow
Stockholm → London → Chennai
Timetable, London time
15:10BA 777 from Stockholm at the gate
14:10BA 35 to Chennai leaves the gate
23 h apart on the timetable, overnight
BA 35 leaves 23 h after BA 777 arrives on the timetable: more than half a day, so not a connection we count.