The UK glider training tells us to treat Vne as a TAS value because of the flutter risks, which must be why I thought that was how it was as standard expressed
This is one of the sideline issues I have with training. Instructors, most likely because of reasoning pased 90% urban legend and 10% understanding, are sometimes training pilots with information which is not in harmony with certification methods, and thus the approved limitations for an aircraft (flight manual information). The result is lesser experienced pilots, doing things in aircarft which conflict with the "approved" procedures for that aircraft. When you challenge the pilot was to why he/she did it that way, they say "'cause I was trained to!". Good answer, but not always correct.
Those of us who write flight manuals, do so to comply with standards which are long established, and define and limit the aircraft in accordance with design and test results. It is frustrating to be reminded that after the effort of exactly wording a flight manual to conform to a standards, and convey exactly what the pilot needs to know about the plane, without unduly limiting that pilot, pilots go and limit themselves more, perhaps for the wrong reasons.
Pilot's training must have a large emphasis on the flight manual and reading and understanding it. This may mean that many instructors have to receive this training first!
Pilots, remind yourself, that you are responsible for understanding and correctly applying, the information in the flight manual for the aircraft you are flying. If in doubt, ask!