What is the M P mintmark on a 1941 Australian Penny?
There is no "MP" mintmark on any Australian Penny.
A 1941 Australian Penny minted in Perth will have a "." after
the "Y" in PENNY (Y.), or a "." between the KG (K.G) on the
reverse.
A 1941 Australian Penny minted in Melbourne will have no mint
mark at all.
The letters HP on the obverse below King Georges head are the
initials of the designer, Thomas Humphrey Paget.
The letters KG on the reverse above the kangaroos tail are the
initials of the designer, George Kruger Gray.