I wasn't seeing mine as 'tableware' in the usual sense of the word - I'd always thought it looked too decorative to be that, but fashions and tastes change so who knows - makes me think of a Celtic cross.
In fact thinking back now, don't believe it was me that showed the plate originally - it was posted by a woman from one of the charity shops, who had been given three, I think, and she was asking for some information so that they could be sold with at least an approximate date and some details about the maker.
So I emailed and asked if I might buy one, to which she agreed - think now I should have bought all that she had - from the comments so far plates may well be less common than we thought.