FR 331 then FR 6875 at Dublin
London Luton → Dublin → Barcelona
Timetable, Dublin time
14:25FR 331 from London Luton at the gate
06:40FR 6875 to Barcelona leaves the gate
16 h 15 apart on the timetable, overnight
FR 6875 leaves 16 h 15 after FR 331 arrives on the timetable: more than half a day, so not a connection we count.