BA 483 then BA 11 at Heathrow
Barcelona → London → Singapore
Timetable, London time
19:25BA 483 from Barcelona at the gate
18:45BA 11 to Singapore leaves the gate
23 h 20 apart on the timetable, overnight
BA 11 leaves 23 h 20 after BA 483 arrives on the timetable: more than half a day, so not a connection we count.