Hello wce and Mowerfreak
This machine dates to the final years -c1968-70

Turner ceased manufacture of lawnmowers in 1970.
The clue here is the 'Safe T' sticker used on the final Valiants.

https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/90536/turner-brochure-c1969.html

wce, this was Turner's first high-arch lawnmower (c1966) and the one that
introduced the poly catcher to Australia - another Turner first.

Cheers
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Jack