A window operator for moving a window sash in a window frame (F) between open and closed positions. The window operator has a mounting plate (14), an elongate threaded member (16) mounted with the mounting plate (14). A drive handle (11) enables a rotational movement to be applied to the elongate threaded member (16). A threaded element (66) is located on the elongate threaded member (16). A hinge (26) with which a window sash can be mounted is attached to a coupling (23) moveable in response to movement of the threaded element (66) on the elongate threaded member (16). The hinge (26) has one arm (28) pivotally coupled to the mounting plate (14). Because arms (24 and 25) of the hinge (26) is attached to the coupling (23), movement of the coupling (23) results in movement of the hinge (26).