An Acting Pilot Officer is a commissioned rank, whereas a Midshipman is not.
Well ... this letter here in front of me, from the Admiralty dated 28 August 1963, says ...
I am commanded by My Lords Commissioners of the Admiralty to inform you that you have been granted a commission on the Supplementary List of the Royal Navy ....
You have been appointed to the Britannia Royal Naval College, Dartmouth, as a Naval Air Cadet with seniority of 17th September, 1963, the date of your entry into the Royal Navy. ...
So if a Naval Air Cadet is commissioned, then a Midshipman certainly is!
MPN11
RN and RAF (Retired)
