BA 389 then BA 802 at Heathrow
Brussels → London → Reykjavík
Timetable, London time
12:05BA 389 from Brussels at the gate
11:45BA 802 to Reykjavík leaves the gate
23 h 40 apart on the timetable, overnight
BA 802 leaves 23 h 40 after BA 389 arrives on the timetable: more than half a day, so not a connection we count.