VS 12 then BA 668 at Heathrow
Boston → London → Marrakesh
Timetable, London time
09:55VS 12 from Boston at the gate
07:35BA 668 to Marrakesh leaves the gate
21 h 40 apart on the timetable, overnight
BA 668 leaves 21 h 40 after VS 12 arrives on the timetable: more than half a day, so not a connection we count.