IB 723 then BA 1338 at Heathrow
Madrid → London → Newcastle
Timetable, London time
18:15IB 723 from Madrid at the gate
16:05BA 1338 to Newcastle leaves the gate
21 h 50 apart on the timetable, overnight
BA 1338 leaves 21 h 50 after IB 723 arrives on the timetable: more than half a day, so not a connection we count.