BA 581 then BA 802 at Heathrow
Milan → London → Reykjavík
Timetable, London time
13:55BA 581 from Milan at the gate
13:45BA 802 to Reykjavík leaves the gate
23 h 50 apart on the timetable, overnight
BA 802 leaves 23 h 50 after BA 581 arrives on the timetable: more than half a day, so not a connection we count.