"The "move object" tool on the Edit menu..." Thanks VirtualSite. Since I very rarely use the edit menu, that explains why I hadn't come across that one. Mind you, thinking about it, the 'hold down y key and move mouse' method operates in the same way to move an object on the y axis - you move the mouse left and right. To be honest it never struck me as strange because that's the same way things work when moving objects on the x and z axes. Because pressing the appropriate key limits movement to a single axis, which may lay in any direction depending on the position and orientation of the camera, it makes sense to me to keep the operation the same for all three axes. There isn't really 'up and down' or 'left and right' in 3D space, just the three axes x, y and z.