Disclosed is a locking arrangement having a first wall defining a first surface and a second wall defining a second surface, with the first and second surfaces abutting each other; a mechanism for locking the first wall against the second wall; and a movable member. The first wall and the second wall are configured to define an enclosed channel for accommodating the movable member such that the movable member is slidable within the channel, and wherein the locking arrangement may assume one of two configurations, in that in one of the two configurations said walls are prevented from moving relative to each other by the movable member and in the other configuration said walls and hence the arms extended therefrom are movable relative to each other.