Plastic set, c1970s

A currently unattributed plastic set, I believe from the 1970s to 1980s.  It is made of a form of plastic which is very familiar - similar to that used for the original "Mastermind" board game, or indeed an original Playmobil pirate ship (both of which I had as a child...and might still have kicking around in a dusty corner). A charming little set, well made and solid to the touch, with interesting non-run-of-the-mill knights.