BA 727 then BA 348 at Heathrow
Geneva → London → Nice
Timetable, London time
11:25BA 727 from Geneva at the gate
15:50BA 348 to Nice leaves the gate
4 h 25 apart on the timetable
The last days
BA 727 and BA 348 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.