BA 52 then BA 870 at Heathrow
Seattle → London → Budapest
Timetable, London time
07:10BA 52 from Seattle at the gate
19:25BA 870 to Budapest leaves the gate
12 h 15 apart on the timetable
BA 870 leaves 12 h 15 after BA 52 arrives on the timetable: more than half a day, so not a connection we count.