I had about a dozen plants I planted in May, came from two sources.
Around 90% of my harvest has been soft and juicy as a runner bean
should be.. The odd one seems to be fat and bulbous and after cooking
I get the odd mouthful of completely undigestible runner bean which I
have to spit out. It's so horrid it's almost putting me off the rest
of the beans, not the taste, the thought.

What's going on?