AC 856 then BA 352 at Heathrow
Toronto → London → Nice
Timetable, London time
08:30AC 856 from Toronto at the gate
20:40BA 352 to Nice leaves the gate
12 h 10 apart on the timetable
BA 352 leaves 12 h 10 after AC 856 arrives on the timetable: more than half a day, so not a connection we count.