BA 773 then SQ 321 at Heathrow
Oslo → London → Singapore
Timetable, London time
22:00BA 773 from Oslo at the gate
21:45SQ 321 to Singapore leaves the gate
23 h 45 apart on the timetable, overnight
SQ 321 leaves 23 h 45 after BA 773 arrives on the timetable: more than half a day, so not a connection we count.