FR 331 then FR 7152 at Dublin
London Luton → Dublin → Santander
Timetable, Dublin time
17:15FR 331 from London Luton at the gate
06:05FR 7152 to Santander leaves the gate
12 h 50 apart on the timetable, overnight
FR 7152 leaves 12 h 50 after FR 331 arrives on the timetable: more than half a day, so not a connection we count.