BA 126 then BA 774 at Heathrow
Doha → London → Oslo
Timetable, London time
07:25BA 126 from Doha at the gate
20:20BA 774 to Oslo leaves the gate
12 h 55 apart on the timetable
BA 774 leaves 12 h 55 after BA 126 arrives on the timetable: more than half a day, so not a connection we count.