BA 545 then SQ 319 at Heathrow
Bologna → London → Singapore
Timetable, London time
21:30BA 545 from Bologna at the gate
20:35SQ 319 to Singapore leaves the gate
23 h 05 apart on the timetable, overnight
SQ 319 leaves 23 h 05 after BA 545 arrives on the timetable: more than half a day, so not a connection we count.