Circular playing cards, although unusual, are by no means rare. The Indian Ganjifa cards are mostly circular in shape. This is doubtless due to the relative ease of making circles of regular shape than rectangles ( To make circles, one only needs a pair of dividers or compasses to trace the designs, whilst drawing rectangles calls for much work involving straightedges, which is wont to be inaccurate).
However, as far as the west is concerned, circular playing cards are more often than not produced as novelties. This particular example is an English pattern. However, some modifications have been made to suit the format.
Notice that the court cards are repeated four times on each card, much like spokes on a wheel. In order for that to be achieved, the figures have to be stripped down a bit, thus making the king of spades look like four skittles!. The indexes are also repeated around the card in a similar fashion
The Joker displays a knight ( St, George?) slaying a dragon.
Note that although the courts have been repeated 4 times, the arrangement of the pips are as with a normal deck.
The pips on the court cards seem to have been inverted