A wall coupling restrains adjacent walls 2 and 3 from displacement over each other. The two walls have coincident apertures 12 and 16. A flexible moulded plastics retaining strip 5 is carried by the wall 2 on its side remote from the wall 3. The strip 5 overlies the aperture 12 and has an end 8 which is secured relative to the wall 2 and an end 7 which is slidable along tracks on the wall 2 in a direction towards and from the end 8. A mid-length region 6 of the strip 5 between its ends 7 and 8 has integral hinges 13 to 15 so that during displacement of the strip end 7 towards the end 8, the region 6 doubles to project through the apertures 12 and 16 and thereby couple the walls 2 and 3 to restrain them from relative displacement. A combination stop/catch can be provided to temporarily retain the strip end 7 in a position where the mid-length region 6 of the strip is in either a folded or an unfolded condition.