So there we have it.
There is no answer and the phrase "avoiding action" means all things to all men.
There is no definitive rule on the issuing or response to the "avoiding action" call. It depends whether you are in controlled airspace receiving a radar control service or elsewhere receiving a Radar Advisory service. It depends on the controllers intonation as to whetther there is urgency and whether the controller is using the phrase to maintain separation or to avoid collision. MATS part 1 is of little help and the controller and the pilot each have only part of the story.
What a way to run a ship!!