The invention provides an anchoring device for anchoring an elongate guide element of an architectural covering and an installing method. The anchoring device includes a body having a rear surface. The body is suitable for attachment to a support structure with the rear surface in close contact with the support structure. The body includes a receiving cavity for receiving the elongate guide element, a first entrance to the receiving cavity and a second entrance to the receiving cavity. The receiving cavity can receive the elongate guide element selectively either through the first entrance, with the rear surface having a first orientation with respect to the elongate guide element, or through the second entrance, with the rear surface having a second orientation with respect to the elongate guide element, and wherein the second orientation is substantially different from the first orientation.