KGV Perfin Identification MM?

First of all, thank you for all of the perfin related posts and scans. Very interesting.
I am a new member so hopefully this is an adequate post and scans below.

I have read some related posts and searched but have not come across a perfin with these letters.

I think it is MM ICO (the O is maybe superscript or a degree symbol?)?
Or I am reading it all wrong (probably upside down). I am sure someone will tell me.

And my apologies I have not properly identified the stamp yet.

Tip: Try to scan or take an image on black background.
Try to offer Watermark and perforation....this does assist.

Format the / = start a new line
Your format would read Perfin MM / I Co

Source:
http://www.perfins.com.au/OZ-Revenu...Perfins.html

User: Mercantile Mutual Insurance Co
Insurance Provider
Address: 16 Martin Place, Sydney, NSW
Revenue Use:
KEDVII 1909-28 issue 4d, 8d, 1/-, 2/-, 3/-, 4/-, 5/-, £1
Numeral 1929-66 issue 4d, 8d, 3/-, 4/-
Rarity Scale:
KEDVII 1909-28 issue 4d R4, 8d R4, 1/- R3, 2/- R3, 3/- R3, 4/- R4, 5/- R3, £1 R4
Numeral 1929-66 issue 4d R3, 8d R4 3/- R3, 4/- R2

Thank you Rod222
I appreciate the information and posting tips.
I am not sure I am understanding the rarity scale in the source provided.
I reviewed their information which was fascinating.
But I don't see mention of the 1 1/2 (3 half pence) denomination or maybe I am not reading it correctly with the abbreviations.
Thank you again.

Turtle,
please excuse my brevity, the rarity scale, et al, I posted, was in reference
to REVENUE STAMPS only.

I cannot confirm the perfin is from the same user on KGV sidefaces, (Postage) but one would assume they are.
The layout in the revenues page, is a little tricky I find.

The Aussie Perfin catalogue is around $180 so we of the challenged wallet, must do with what we can grind from the internet.

The value of your three halfpence KGV sideface postage stamp, is just a few cents, unless the stamp itself has a catalogued flaw of some rarity.

Turtle2900,
Your perfin is classified as MMICO.2 in the 'Handbook of Australian Private Perfins', Edited by John Mathews.

Rated C (common in the world of private perfins - although any 'common' private perfin is far less common than the 'non-perfin' version of a stamp)

Other information about this perfin from the book:

Mercantile Mutual Insurance Co.
120 Pitt Street, Sydney NSW
Found used on Commonwealth issues 1929-37.