FB 851 then BA 828 at Heathrow
Sofia → London → Dublin
Timetable, London time
12:10FB 851 from Sofia at the gate
08:25BA 828 to Dublin leaves the gate
20 h 15 apart on the timetable, overnight
BA 828 leaves 20 h 15 after FB 851 arrives on the timetable: more than half a day, so not a connection we count.