Hello Hepsibar
It's great another A-V is saved.

Dating is problematic - and better info will probably be
the numbers stamped on the flywheel.

That this carries an 'X' number is important; meaning
it was Australian 'built'.

The record I have says this was a Condeco spec. ...
meaning the engine is original to your machine.
131X appears early in the record too:

[Linked Image]

The problem is that no one seems to know whether AUS
built originally meant 'assembled' or 'manufactured'.

I have little idea when the 'X' engines first appeared.

Villiers AUS were clearly assembling engines from imported parts
from probably the mid-1950s. Early AUS Villiers manufacture
was about changing that parts ratio - as more parts were made here.

Your engine is a Villiers MK2 Midget, and my best guess is that
your mower dates to the mid-to-late 1950s.

Cheers
---------------------
Jack