BA 228 then BA 864 at Heathrow
Baltimore → London → Prague
Timetable, London time
07:05BA 228 from Baltimore at the gate
19:50BA 864 to Prague leaves the gate
12 h 45 apart on the timetable
BA 864 leaves 12 h 45 after BA 228 arrives on the timetable: more than half a day, so not a connection we count.