I had to go and sit in the car to see what I do to shut the door!!
So, open the door using the inside lever, sit in the car and pull the door shut using the black lever on the lock.
The MMC door locks are from the rear door of a Land Rover Discovery and are intended to be slammed shut. They are Farmer/Squaddie proof. So a gentle shut is liable to result in a door not properly shut. The door needs a slam, not a soft pull....