BA 755 then BA 802 at Heathrow
Basel → London → Reykjavík
Timetable, London time
12:00BA 755 from Basel at the gate
11:45BA 802 to Reykjavík leaves the gate
23 h 45 apart on the timetable, overnight
BA 802 leaves 23 h 45 after BA 755 arrives on the timetable: more than half a day, so not a connection we count.