The mechanical locks have been engaged manually at exit of the vehicle. The locks on the old cars could be engaged on the individual doors by pressing or pulling a stem along the upper inner surface of the interior door panel.I'm being thick here. The car is locked. The key is inside the car. The car has been locked from the outside by using the key....?
Cars so equipped could also be locked and unlocked manually with the key inserted in the exterior mechanism.
The picture is what mine looked like (different color).