Ascend Charlie.
The simple version is that the Angle of Attack is the same but strictly :-
IGE the IF is reduced so the RAF lies closer to the Plane of Rotation. Therefore both the Lift(90degrees to the RAF) and Total Reaction vectors are moved closer to the axis of rotation so the component felt along the axis of rotation is larger. For a given AOA the TR is the same magnitude but at a lower BPA the inclination is towards the AOR so there is a greater vertical component. OGE and IGE the Vertical component needs to be the same so a very small reduction in AOA is needed to achieve this.