BA 371 then FI 451 at Heathrow
Toulouse → London → Reykjavík
Timetable, London time
13:15BA 371 from Toulouse at the gate
12:15FI 451 to Reykjavík leaves the gate
23 h apart on the timetable, overnight
FI 451 leaves 23 h after BA 371 arrives on the timetable: more than half a day, so not a connection we count.