QR 3530 then U2 2324 at Barcelona
Bilbao → Barcelona → London Luton
Timetable, Barcelona time
12:45QR 3530 from Bilbao at the gate
10:25U2 2324 to London Luton leaves the gate
21 h 40 apart on the timetable, overnight
U2 2324 leaves 21 h 40 after QR 3530 arrives on the timetable: more than half a day, so not a connection we count.