[PeterVerney]

Re "Judy". Once the navrad had a firm contact he had to keep up a good commentary to his pilot which consisted of position reports, i.e. "target at 40 port slightly above range 4 miles". Or orders, i.e. "Port hard" which he required to be obeyed instantly by the pilot, as he was inevitably behind the true position. I.e. the delay in appreciating the need to turn and the lag between issuing the order and the pilot obeying.
Life could become very fraught and the last thing the navrad needed was unnecessary remarks from the GCI cutting across his commentary. A typical navrad remark would be, "for Chrissake tell him Judy".
It was then that absolute trust each way between pilot and navrad was essential to a successful interception, as mistakes led swiftly to failure and the navrad had to be obeyed immediately. The navrad for his part had to realise immediately if he had made a wrong call and do something about it at once. There was no time for explanation or recrimination until the interception was completed or abandoned. Collisions with the target did occasionally occur.