Many thanks for this link. I was not aware that such detailed information existed on the fletcher uniform system. I was still operating under the 'mike okuda 1' system where a RADM wore a 'two bar' pip. Hence my belief that Kirk was a ADM by STII.
Given the information on the original design of the fletcher uniforms, then it would seem likely that Kirk remained a RADM until his demotion. This is also fitting with the writer's intent of having Kirk as an 'unhappy desk jockey' by STII.
I am surprised that there is such ambiguity about the 'maroon jacket, ranks and insignia. It seemed like a reasonably logical and consistent system during my recent rewatch of the TOS movies.
Thanks for the discussion.