FR 6921 then BA 485 at Barcelona
Dublin → Barcelona → London Heathrow
Timetable, Barcelona time
19:20FR 6921 from Dublin at the gate
17:00BA 485 to London Heathrow leaves the gate
21 h 40 apart on the timetable, overnight
BA 485 leaves 21 h 40 after FR 6921 arrives on the timetable: more than half a day, so not a connection we count.