who designed this chair - parker knoll-ish?  

could be
Scandart of High Wycombe, UK

Yes
the arms have the look of a Scandart rocker I've seen..
But whether they exported to SA, I don't know.
There are inummerable Parker Knoll 'designs' but this doesn't look like one to me.

Certainly VERY similar to,
if not the same as the Scandart chair :

That's it!
Thanks guys! I've had this chair for ages & hours of trawling books & the net came up with nothing! took the forum just a few hours! awesome - thanks!

FYI, it's slightly different
Note the "bend" in the back. On one chair the arms connect above it, on the other below it.
It could still possibly be Scandart, but is definitely not the same model than the graffiti chair.

The Scandart High Wycombe armchair frame.
Hi there my name is Josh,Scandart Lover. Are you interested in getting rid of this wooden frame? If you are interested my email address is: jcrocker.isavailable at yahoo.co.uk. I will be able to give you an offer for it depending on the condition.
I hope to hear from you 🙂
Regards

It's
in South Africa 😉