AI 3318 then BA 134 at Mumbai
Patna → Mumbai → London
Timetable, Mumbai time
11:15AI 3318 from Patna at the gate
07:40BA 134 to London leaves the gate
20 h 25 apart on the timetable, overnight
BA 134 leaves 20 h 25 after AI 3318 arrives on the timetable: more than half a day, so not a connection we count.