UA 27 then BA 756 at Heathrow
Denver → London → Basel
Timetable, London time
09:40UA 27 from Denver at the gate
09:25BA 756 to Basel leaves the gate
23 h 45 apart on the timetable, overnight
BA 756 leaves 23 h 45 after UA 27 arrives on the timetable: more than half a day, so not a connection we count.