Thats interesting about the Austen, I never heard about that one either.
Did they ever do a silenced barrel version of either the Austen or the Owen, like the Sten Mk2S?
from that wiki
There was a suppressed version made for use by Z Special Force.
An improved version, the Mark II Austen, which had an accompanying dagger type bayonet that was designed to fit over the muzzle compensator was designed, expanding on the use of diecasting, of which 200 were built.
The Austen never achieved the level of popularity that the Owen gun achieved. This was largely because the Owen was a very reliable weapon and although the Austen was an improvement on the basic Sten, it was never able to achieve the Owen's reliability. Additionally, it has been asserted that the Owen was much more suited to jungle warfare. No doubt the Austen's side mounted magazine and bolt proved a hindrance to soldiers in the jungle, as this aspect necessarily meant that the working parts were more exposed to dirt and therefore prone to fouling due to the cocking slot's position on the right hand side of the body.