IB 597 then BA 389 at Brussels
Madrid → Brussels → London Heathrow
Timetable, Brussels time
11:30IB 597 from Madrid at the gate
11:25BA 389 to London Heathrow leaves the gate
23 h 55 apart on the timetable, overnight
BA 389 leaves 23 h 55 after IB 597 arrives on the timetable: more than half a day, so not a connection we count.