FB 851 then EI 155 at Heathrow
Sofia → London → Dublin
Timetable, London time
12:10FB 851 from Sofia at the gate
09:50EI 155 to Dublin leaves the gate
21 h 40 apart on the timetable, overnight
EI 155 leaves 21 h 40 after FB 851 arrives on the timetable: more than half a day, so not a connection we count.