That's right, Lithgow marked their components with a star with an A in it.
This looks to be a tiny star. My guess is that it is not the Lithgow mark.
Another use for a very similar star marking was on the sight block or sight leaf for the retrofitted upgrades to the MLE in 1902 for sight corrections for bullet drift.
These are definitely cut off plates as fitted to the Mk.II MLM or LMC Mk.I. Note the bevel that spans the entire rear edge of the plate and the lack of a cutout to clear the larger right magazine feed lip of the Sht.LE.
Now I have heard of long Lee Enfield barrels produced by Lithgow in later years to keep the fleet of long Toms in service. Same dimensions and profile but a Sht.LE style nocks form flat. Never seen one in the flesh, don't know how they were marked.
I am still learning about Australian rifle production. It is a fascinating study in itself. There are some nice specimens in Canada with collectors. Many still on the loose and not recognised for their collectability. I recently missed a intact 1913 Lithgow smle that sold for $125Cdn. The buyer wants a hunting rifle for moose, he wants a scoped synthetic stocked rifle. EEEK! So I am trying to trade him for an already sportered one.