FR 3976 then BA 829 at Dublin
Barcelona → Dublin → London Heathrow
Timetable, Dublin time
19:00FR 3976 from Barcelona at the gate
11:00BA 829 to London Heathrow leaves the gate
16 h apart on the timetable, overnight
BA 829 leaves 16 h after FR 3976 arrives on the timetable: more than half a day, so not a connection we count.