ESDU 67006 presents the equations of motion in the form usually employed for rolling manoeuvres when inertia coupling effects become important and@ in particular@ discusses in detail the simplification which results from imposing the constraint that rate of roll is constant. The conditions for stability of the resulting motion are deduced. Further approximations are then introduced which lead to the conditions for stability as presented by Phillips and the case of an aircraft with zero rotary damping terms is considered in more detail. The elegantly simple results for this case permit a ready discussion of the main factors affecting the stability and thereby supplement the qualitative discussions of ESDU 67005. A stability boundary diagram is a convenient method of presenting such results and the form it takes for the case with zero damping is discussed.