BA 365 then BA 243 at Heathrow
Marseille → London → Mexico City
Timetable, London time
13:25BA 365 from Marseille at the gate
12:45BA 243 to Mexico City leaves the gate
23 h 20 apart on the timetable, overnight
BA 243 leaves 23 h 20 after BA 365 arrives on the timetable: more than half a day, so not a connection we count.