BA 138 then BA 546 at Heathrow
Mumbai → London → Bologna
Timetable, London time
07:05BA 138 from Mumbai at the gate
20:25BA 546 to Bologna leaves the gate
13 h 20 apart on the timetable
BA 546 leaves 13 h 20 after BA 138 arrives on the timetable: more than half a day, so not a connection we count.