EC 8064 then U2 8419 at Gatwick
Barcelona → London → Nice
Timetable, London time
14:25EC 8064 from Barcelona at the gate
08:25U2 8419 to Nice leaves the gate
18 h apart on the timetable, overnight
U2 8419 leaves 18 h after EC 8064 arrives on the timetable: more than half a day, so not a connection we count.