OS 335 then BA 868 at Heathrow
Vienna → London → Budapest
Timetable, London time
14:05OS 335 from Vienna at the gate
13:00BA 868 to Budapest leaves the gate
22 h 55 apart on the timetable, overnight
BA 868 leaves 22 h 55 after OS 335 arrives on the timetable: more than half a day, so not a connection we count.