Sorry this is why I put "government use"
A prefect (French: préfet) in France is the state's representative in a department or region. Subprefects (French: sous-préfets) are responsible for the subdivisions of departments, arrondissements. The office of a prefect is known as a prefecture and that of a sub-prefect as a subprefecture. Prefects are appointed by a decree of the President of the Republic in the Council of Ministers, following the proposal of the Prime Minister and the Minister of the Interior. They serve at the Government's discretion and can be replaced at any meeting of the Council.
From 1982 to 1988 prefects were called commissaires de la République (the Republic's commissioners) and the sub-prefects commissaires adjoints de la République.
My understanding- government use (serve at the government's discretion got me) (post office fits in there :)
As for the 1f you could be right, far as I can tell the only way to tell the difference is the cancellation
I believe it was on france&colonies I read about the military franking
There is a similar 9ish mark (but could be something else) and the two types of ink seemed strange
I will have to find that link again :) can't find the link yet, but found a image of the "9"
Again I could be wrong! But I thought worth a try :)