BA 553 then BA 742 at Heathrow
Rome → London → Geneva
Timetable, London time
15:10BA 553 from Rome at the gate
15:05BA 742 to Geneva leaves the gate
23 h 55 apart on the timetable, overnight
BA 742 leaves 23 h 55 after BA 553 arrives on the timetable: more than half a day, so not a connection we count.