Royal China "Pink Orchid" CAKE PLATE "National Brotherhood of Operative Potters"

Beautiful vintage cake plate by Royal China in the "Pink Orchid" pattern.  The words "National Brotherhood of Operative Potters" and "N-11" are marked on the back.  I am not an expert so cannot gauge condition except to say that to me it seems excellent for its probable  age.  There appear to be no chips or cracks, however there is some crazing (I think that's what it's called) predominantly along the rim.   Please note that the plate had not been cleaned when these photos were taken.  I have since washed it multiple times.  It looks much better, however there are concentrick circles of what looks like deeply embedded discoloration (as you can see in the picture) that I have not yet managed to get out.    I think that just gives it a more "vintage" look- still very pretty.    Interested to hear any information on what this may be worth, and delighted to sell for a fair price.  Thanks in advance!