So ..eventually ordered one of these :-
https://www.ebay.co.uk/itm/113692160606
DPDT switches ..centre off
So three positions.
The theory/hope being.
The centre position is off for all ..no connections made...thus the HC533 defaults to Octagon mode.
I can use one side/pole of the switch to hook up to the JP1 jumper on the HC533 ..
On = Octopussy
Off = Octagon
Centre off ..(the other pole) disconnects power to the CF adapter ..but in either Up or Down position applies power to the CF card ..and I retain the HC533s ability to supply CF power and select Either Octopussy or Octagon.
Hope that makes sense.
rgds
VS