A small point but may help understanding. I was always told that rather than think of a 'bubble' around an aircraft, think of a long pointer expanding into a cone ahead of the aircraft. That is the 'tickling stick' that will cause the possible confliction warnings due to closing flight paths. Hence the problem where a/c in the circuit at Kinloss may 'tickle' the TCAS on a/c approaching Inverness even though the circuit a/c is in a turn onto downwind. Unfortunately, we never got the chance to worry about such issues on the MRA4 in the end.