LL 5107 then FR 7808 at Barcelona
Prague → Barcelona → London Luton
Timetable, Barcelona time
13:15LL 5107 from Prague at the gate
12:45FR 7808 to London Luton leaves the gate
23 h 30 apart on the timetable, overnight
FR 7808 leaves 23 h 30 after LL 5107 arrives on the timetable: more than half a day, so not a connection we count.