This pack has been a bit of a mystery item in my lot for a while. I have not seen another like it. It is obliviously in the pattern 37 style - With a few standout differences, no brass/metal hardware eyelets etc.
The cotton webbing material is also much lighter and softer. There are no markings visible.
For comparison, note a pat 37 pack (post WWII, note the black metal hardware) and a pattern 08 pack (almost certainly used in WWII - dyed green).
If I recall correctly, this pack came from a group which I believe was used by an Australian cadet circa 1970, who interestingly had also been issued a WWII Vintage M1 helmet! WCCU - Waverley College Cadet Unit.