A locking mechanism (10) and an animal containment apparatus (14) incorporating the mechanism. The mechanism includes a locking arrangement (12) including a linear passage (24) with end sections (30) and a mid-section (32) of reduced width. The mid-section and at least part of the end sections are defined on opposite sides by first and second members. A locking member (36) is movably located in each end section and due to its size cannot pass through the mid- section but can freely pass along the end sections. If the locking member is urged into the mid-section, it will jam between first and second members to engage the locking mechanism, thereby preventing relative linear movement between the first and second members. An engagement member (38) is provided locatable in the mid-section and selectively movable along the mid-section to urge a respective one of the locking members out of the mid-section towards an end section, to disengage the locking mechanism.