Abstract: A louvre shutter adapted to be assembled from elements forming a kit. The elements are so adapted that the shutter dimensions can vary, enabling the shutter to be installed within a window frame that falls within a predetermined range of sizes. The side rails of the shutter incorporate elongate channels for receiving elongate support members. The support members have a plurality of apertures that journal elongate pinion gears projecting from the louvres. The combination of the support rails, louvres, and pinion gears forms a sub-assembly that can be received within the side rails and top rails of the shutter frame. The support members include channels that receive gear racks. The pinion gears mesh with the gear racks enabling synchronous rotation of the louvres. The pinion gears perform the additional function of operating as spindles for the louvres. The dual functionality of the pinion gears reduces the complexity of component parts in the kit and facilitates assembly.