A folding wing having a wing tip device (3) rotatable between flight and ground configurations, about an Euler axis of rotation (11). The wing tip device (3) and a fixed wing (1) are separated along an oblique cut plane (13) passing through the upper and lower surfaces of the folding wing. A rotational joint (15) for coupling the wing tip device (3) to the fixed wing (1) during rotation between the ground and flight configurations. The rotational joint includes a follower (17a) and a guide (17b), one which being fixed relative to the wing tip device and the other being fixed relative to the fixed wing. The follower and guide interlock such as by interlocking rings. The follower is received in the guide such that during rotation between the ground and flight configurations the follower moves along the arcuate path defined by the guide.