attractive display Anne - commemorative plates, roughly post the 1930's, are still fairly common in the south of the U.K ............... Eliz. II, George V and VI - although I suspect they aren't period pressings - more likely someone using moulds at a later date as the condition seems often to be too good.
Royal commemorative pieces, unless old, lack popularity in the main - perhaps this might change when the present incumbent departs - nothing like overstaying your welcome to engender apathy - perhaps ceramic items are more popular than glass.
You don't appear to have any Wedgwood pieces? - Stennett-Willson was very keen I seem to remember, and he knocked out a wide range of items - some very expensive - although much more recent of course than the pieces we've been discussing.
However, those commemorative pressed mugs/tankards etc. certainly aren't anywhere near as common as ten years ago - someone must have them all.
Sorry to see the plate is cracked