FB 851 then BA 480 at Heathrow
Sofia → London → Barcelona
Timetable, London time
12:10FB 851 from Sofia at the gate
10:55BA 480 to Barcelona leaves the gate
22 h 45 apart on the timetable, overnight
BA 480 leaves 22 h 45 after FB 851 arrives on the timetable: more than half a day, so not a connection we count.