Mason's Patent Ironstone China

I recently acquired a Mason's Patent Ironstone China plate with the two handles as pictured. It is about 9 1/4 inches square (if you don't consider the handles). The Maker's Mark on my plate simply says Strathmore England. In researching this piece I can find many like-items, and even looking exactly the same size, description, coloring, but each one of them include Strathmore England ....."Permanent, Detergent Proof Decoration". See images of the differences in Maker's Marks.
My question is does one represent an older plate, or more rare? I appreciate any thoughts or explanation for the difference.

Thank you.