A louvre window system has an end clip (10) which is formed with at least one internal drainage channel (14) which can drain water through the end clip (10). A number of such clips can rotate between an open position and a closed position. The clips (10) are aligned when in the closed position which insures that water can drain from an upper clip through a lower clip. The clips (10) have a low friction design which enables a larger number of louvers to be rotated by a single handle (55) without placing too much load on the handle and on the louvre operating mechanism. A simple efficient louver operating mechanism (27; 37) is used to operate the end clips.