From my manual:
WARNING
Only for the United Kingdom: if the vehicle has been locked with the key or with KEY- LESS-GO, the double lock function is activa- ted as standard. It is then not possible to open the doors from inside the vehicle.
Therefore, do not leave any people behind in the vehicle, particularly children, elderly peo- ple or people requiring special assistance. As a result, they may not be able to free them- selves in the event of an emergency. They could be seriously or even fatally injured by prolonged exposure to extremely high or low temperatures, for example. In this case, res- cuing people from outside the vehicle is diffi- cult.
Deactivate the interior motion sensor before you lock the vehicle. The doors can then be opened from the inside after the vehicle has been locked from the outside.