Australia 2/- Kangaroo 1913

Hi to all
As far as I can establish this stamp is an SG 12
It has a Gibbons WMK 2 and Perforation of 12
It is a Die II and is from 1913
It has a break in the coast of Queensland, and the Great Australian Bight and for those who live in Victoria, there is a Brown dot at the base of Victoria which I am calling Phillip Island.
What puzzles me is the number some-one has pencilled on the back
it is 48K and they have a pounds shilling and pence value of 45/- pencilled also so it was done prior to Decimal Currency in 1966.
This and many others were part of an estate collection that I purchased.
Can anyone tell me what the 48K refers to, it seems to be a catalogue number but it is not Gibbons, maybe from ACSC but I do not have a copy of the volume with Roos.
Any information would be greatly appreciated.
Regards
Horamakhet

Not in ACSC, could only find 40K.

Sometimes numbers change over the years.

Hi KGV Collector

What does it say about 40K anywa?
Regards
Horamakhet

It is a Tasmanian shaped island Top Below LI in Australia. Nearly the size of the letters in postage.

Hope it helps.