BA 391 then BA 197 at Heathrow
Brussels → London → Houston
Timetable, London time
16:15BA 391 from Brussels at the gate
15:25BA 197 to Houston leaves the gate
23 h 10 apart on the timetable, overnight
BA 197 leaves 23 h 10 after BA 391 arrives on the timetable: more than half a day, so not a connection we count.