BA 753 then BA 476 at Heathrow
Geneva → London → Barcelona
Timetable, London time
10:00BA 753 from Geneva at the gate
08:20BA 476 to Barcelona leaves the gate
22 h 20 apart on the timetable, overnight
BA 476 leaves 22 h 20 after BA 753 arrives on the timetable: more than half a day, so not a connection we count.