SirToppam and Oggin
On a purely historical note, I believe that the original basis for automatic promotion to Lieutenant Commander was that, prior to 1914, the Lieutenants' List was divided between those under and over eight years' seniority respectively. The rank of Lt So, Cdr was introduced as a further distinction and thus a Lt Cdr was in a sense originally deemed to be a "senior" Lieutenant rather than a "junior" Commander in the way a Lieutenant Colonel is a "junior" Colonel, at least before the need for equivalence arrived when the Light Blue were invented, sorry, formed.
Sadly, this adds little or nothing to the real and very important current issue, and we can only hope for the best for those most affected
by whatever finally emerges from the Madhouse.
Jack