DL 5603 then BA 212 at Boston
Madison → Boston → London
Timetable, Boston time
18:52DL 5603 from Madison at the gate
18:35BA 212 to London leaves the gate
23 h 43 apart on the timetable, overnight
BA 212 leaves 23 h 43 after DL 5603 arrives on the timetable: more than half a day, so not a connection we count.