BA 903 then BA 494 at Heathrow
Frankfurt am Main → London → Barcelona
Timetable, London time
17:25BA 903 from Frankfurt am Main at the gate
16:40BA 494 to Barcelona leaves the gate
23 h 15 apart on the timetable, overnight
BA 494 leaves 23 h 15 after BA 903 arrives on the timetable: more than half a day, so not a connection we count.