Abstract: An automatic locking device is disclosed which may be used to secure a rear-facing auxiliary seat in a raised position in a station wagon. The locking device includes an elongate engagement member which is arranged to be rotatable about its longitudinal axis between a normal position and a release position. The engagement member is provided with notches which are adapted to cooperate with teeth on a pair of jaws in a receiving arrangement. The notches and the teeth are so shaped that when the engagement member is in its normal position, the engagement member can be inserted into the receiving element and withdrawal is prevented by interaction between the notches and the teeth.