FR 2508 then U2 2326 at Barcelona
Cologne → Barcelona → London Luton
Timetable, Barcelona time
21:45FR 2508 from Cologne at the gate
20:55U2 2326 to London Luton leaves the gate
23 h 10 apart on the timetable, overnight
U2 2326 leaves 23 h 10 after FR 2508 arrives on the timetable: more than half a day, so not a connection we count.