Motor vehicle closure locking device

A locking device for a boot flap or door of a motor vehicle, comprising a lock cylinder for mechanical unlocking and locking of a lock with a key;

• an additional bolt operatively arranged to act along with the lock on a closing member of the flap or door, which closing member is separate from the lock and which, during the locking of the lock, can be brought into a securing position in which, by positive engagement into the closing member, the additional bolt prevents the flap or door from being opened, even after the lock has been broken open, and, during the unlocking of the lock, is brought into a release position in which the flap or door can be opened;
• and a spring-loaded detent member which is arranged complementary with the closing member and which prevents the additional bolt from being brought into its securing position, with the flap or door opened, until the closing member is brought into its end position corresponding to the closed position of the flap or door, wherein the additional bolt is prestressed by a spring in the direction of the securing position and is movable mechanically into its release position counter to the force of the spring by a linkage lever operatively connected to the lock cylinder via a free-play connection configured to provide lost motion between the linkage lever and the lock cylinder, which linkage lever maintains the additional bolt in the release position with the lock being unlocked such that the key can be rotated between an unlocking position and a neutral key withdrawal position without change in the release position of the additional bolt.