Pix of commemorative pressed pieces showing the P.o.W. plumes/feathers, seem thin on the ground, and I can find only a couple of examples in my books. Henry Greener produced a bowl and plate in clear glass (the bowl shows the classic spelling error of 'Wales's), and Davidson also did a clear glass plate of sorts. Although not one of the celebratory occasions that Bernard mentions, these clear glass pieces were issued specifically to commemorate his Silver Wedding Anniversary in 1888 - but no luck with a black spill vase.
It would appear that the pix from Anne E. B.'s link have disappeared, so hope people won't mind me adding some of my cauldron. As Anne says, it appears that not all cauldrons are the same shape/design. You can see the thistle mark and concentric cirlces on mine, and it may well be that as Keith's are without the mark, then possibly a different factory.