IB 983 then U2 8843 at Gatwick
Madrid → London → Reykjavík
Timetable, London time
10:50IB 983 from Madrid at the gate
08:00U2 8843 to Reykjavík leaves the gate
21 h 10 apart on the timetable, overnight
U2 8843 leaves 21 h 10 after IB 983 arrives on the timetable: more than half a day, so not a connection we count.