While I haven't grown "Johns Polish Purple", the description sounds very much like another bean I grew in 2008, "Olteanu's Romanian Yellow". It too has yellow pods with the characteristics you describe, and shiny purple seeds with white blotches. In size, shape, and appearance, the beans look somewhat like a purple version of "Calypso". It was actually sent to me as a runner bean, probably because of the purple color; but the emergent cotyledons & flower structure identify it as P. vulgaris.

The variety didn't leave a very good impression with me. I found the pod taste & texture to be inferior, and the dry seed yield was small. But then, it was grown in the worst location in my least fertile plot. I hope to give it a better evaluation soon, in my more fertile rural plot.

I realize this may not have answered your question, Keith. Is it possible to post a photo of the seed?

i am a technological neanderthal as far as posting pictures.
i haven't seen a bean this shade of purple before, with the white splotch being on the upper back of the bean almost like a cap. flavor was pretty good. tom seemed to like it.
i have a few seeds to spare if interested.

keith

Here's a picture of John's Polish Purple Pod.

... that should read John's Polish Purple Pole Bean, brain and fingers don't seem to be co-operating at the moment:(.