FB 851 then SK 532 at Heathrow
Sofia → London → Stockholm
Timetable, London time
16:55FB 851 from Sofia at the gate
13:55SK 532 to Stockholm leaves the gate
21 h apart on the timetable, overnight
SK 532 leaves 21 h after FB 851 arrives on the timetable: more than half a day, so not a connection we count.