UJ, Thanks for "Post 17" I had missed that before.
To go back to the original question. Whilst not quite the same I do know of two Lt/Cdrs RNR who have both been promoted to Cdr whilst on the Retired List. One so he looked more important as High Sheriff of his county of residence and another to fullfill duties on his FTRS job that were more in line with his civvy profession than his naval specialisation. (The former officer's promotion may be an honourary one.) In addition to all that, Mrs DD retired as a Lt/Cdr but is on the List as a Cdr as she had held acting rank for more than 2 years.