A locker for a delivery or collection system, comprising a storage chamber, an access panel for the storage chamber and an authorising unit for authorising access to the storage chamber via the access panel; the locker further comprising means for recording delivery or collection of goods from the storage chamber wherein the authorising unit comprises: a locking mechanism for locking the access panel comprising a first component integral to a frame portion of the storage chamber and a receiver plate mounted on the access panel, said first component comprising a lock bolt and a lock barrel, the lock bolt being moveable between an extended and a retracted position; the receiver plate, having an extension plate extending at an angle from a main body of the receiver plate, the receiver plate including a bolt catch hole for engaging the lock bolt and a stop member slideably mounted on the receiver plate in the region of the bolt catch hole, the stop member having a curved edge extending obtusely from the stop member, wherein in an open state, the access panel is opened and the lock bolt is in an extended position, not engaging the bolt catch hole; and in a closed state but unlocked state the access panel is closed and the stop member is positioned over the bolt catch hole and the lock bolt is in a retracted position and cannot extend into the bolt catch hole; in a locked state, the acces panel is closed and the lock bolt is in an extended position with the lock bolt engaging the bolt catch hole and wherein moving from the closed state but unlocked state, to the locked state the access panel is opened to the open state and when the access panel is closed the extended lock bolt engages the curved edge of the stop member to push the stop member to a position proximal to the bolt catch hole so that the lock bolt engages the bolt catch hole. a locking mechanism for locking the access panel comprising a first component integral to a frame portion of the storage chamber and a receiver plate mounted on the access panel, said first component comprising a lock bolt and a lock barrel, the lock bolt being moveable between an extended and a retracted position; the receiver plate, having an extension plate extending at an angle from a main body of the receiver plate, the receiver plate including a bolt catch hole for engaging the lock bolt and a stop member slideably mounted on the receiver plate in the region of the bolt catch hole, the stop member having a curved edge extending obtusely from the stop member, wherein in an open state, the access panel is opened and the lock bolt is in an extended position, not engaging the bolt catch hole; and in a closed state but unlocked state the access panel is closed and the stop member is positioned over the bolt catch hole and the lock bolt is in a retracted position and cannot extend into the bolt catch hole; in a locked state, the acces panel is closed and the lock bolt is in an extended position with the lock bolt engaging the bolt catch hole and wherein moving from the closed state but unlocked state, to the locked state the access panel is opened to the open state and when the access panel is closed the extended lock bolt engages the curved edge of the stop member to push the stop member to a position proximal to the bolt catch hole so that the lock bolt engages the bolt catch hole. said first component comprising a lock bolt and a lock barrel, the lock bolt being moveable between an extended and a retracted position; the receiver plate, having an extension plate extending at an angle from a main body of the receiver plate, the receiver plate including a bolt catch hole for engaging the lock bolt and a stop member slideably mounted on the receiver plate in the region of the bolt catch hole, the stop member having a curved edge extending obtusely from the stop member, wherein in an open state, the access panel is opened and the lock bolt is in an extended position, not engaging the bolt catch hole; and in a closed state but unlocked state the access panel is closed and the stop member is positioned over the bolt catch hole and the lock bolt is in a retracted position and cannot extend into the bolt catch hole; in a locked state, the acces panel is closed and the lock bolt is in an extended position with the lock bolt engaging the bolt catch hole and wherein moving from the closed state but unlocked state, to the locked state the access panel is opened to the open state and when the access panel is closed the extended lock bolt engages the curved edge of the stop member to push the stop member to a position proximal to the bolt catch hole so that the lock bolt engages the bolt catch hole.