IB 721 then BA 928 at Heathrow
Madrid → London → Hannover
Timetable, London time
17:15IB 721 from Madrid at the gate
16:10BA 928 to Hannover leaves the gate
22 h 55 apart on the timetable, overnight
BA 928 leaves 22 h 55 after IB 721 arrives on the timetable: more than half a day, so not a connection we count.